Sam will be twice as old as his sister next year. Right now, Sam is 10 yrs older. How old is Sam?

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  • Опубликовано: 23 дек 2024

Комментарии • 42

  • @georgecattani7199
    @georgecattani7199 23 часа назад +6

    EZ1. X represents sis, (X-10)+1 = (X-10)+1 +(X+10)+1 / 2 . 2(X-10)+1 = X-9+X+11 . In short 2X=20 X=10 Sam is 19 now sis is 9 next year Sam is 20 sis is 10

  • @stevendebettencourt7651
    @stevendebettencourt7651 День назад +5

    Alright, word problem algebra, very good. Let’s dig in.
    Here is the relevant info in bulletpoint form:
    -1.) Sam is 10 years older than his sister now
    -2.) In one year, Sam will be twice as old as his sister.
    -3.) We need to determine, if possible, Sam’s age now.
    Let’s start making equations. From point 1:
    s = t + 10, where s is Sam’s age now and t is his sister’s age now.
    From point 2:
    s + 1 = 2 * (t + 1) = 2t + 2
    Solve this for s:
    s = 2t + 2 - 1 = 2t + 1
    Notice we have two equations for the value of s. Set them equal to each other:
    t + 10 = s = 2t + 1
    And now solve for t (remember this is not going to be our final answer):
    t + 10 = 2t + 1
    2t - t = 10 - 1
    t = 9
    Plug this into our first equation:
    s = t + 10
    s = 9 + 10
    s = 19
    And there is point 3 resolved: Right now, Sam is 19 years old.

    • @gavindeane3670
      @gavindeane3670 18 часов назад

      You over-complicated it. The equation from point 2 is
      s + 1 = 2 × 10
      which very rapidly gives you s = 19.

  • @tomtke7351
    @tomtke7351 День назад +6

    gotta translate words to equations
    Variables:
    A: Sam's Age
    B: Sister's Age
    Equations:
    Eq.1: A = B + 10
    Eq.2: A + 1 = 2×(B+1)
    A + 1 = 2B + 2
    A = 2B + 1
    Set Eq.1 = Eq.2
    B+10 = 2B+1
    9 = B
    use Eq.1 to find A
    Eq.1: A = B + 10
    A = 9 + 10
    = 19
    VERIFY by Eq.2
    Eq.2: A = 2B + 1
    19 =? 2(9) + 1?
    19 =❤ 19✔️

    • @mylittlepitbull3143
      @mylittlepitbull3143 День назад

      Same way I solved it but I used the letters b and s, for brother and sister.
      I was going to use s for Sam but then sister started with an s

  • @srjwaugh
    @srjwaugh День назад +3

    This took me all of 1 second to solve this.

  • @bazkeen
    @bazkeen День назад +7

    19 years old now. His Sister is 9 Therefore next year his sister will be 10 and he will be 20

  • @EricWells-s2p
    @EricWells-s2p День назад +2

    Since we were asked for Sam's age (today), why not allow the variable "X" to be Sam's age, rather than Sam's sister's age? A final math step can be avoided!

    • @davidwilliams1060
      @davidwilliams1060 23 часа назад

      Yes. However some people might start out trying to work with the sister’s age as X and forget the final step. His way highlights that potential issue.

  • @jald910
    @jald910 18 часов назад +1

    I could have come with an equation and solved for the age(s), but I solved it in my head too quick. I took math in the 1960’s. My grandparents would have been in the early 1900’s.

  • @mylittlepitbull3143
    @mylittlepitbull3143 День назад +2

    Same way I solved it but I used the variables B and s for brother and sister.

  • @gavindeane3670
    @gavindeane3670 18 часов назад

    This is not an algebra word problem. This is a 2 times table problem.
    If Sam is 10 years older than his sister now then he will still be 10 years older than his sister next year. That's how time works.
    Next year Sam's age is 2×10 = 20 so currently Sam is 19.

  • @russelllomando8460
    @russelllomando8460 День назад

    great explaination thanks.

  • @donwilson1307
    @donwilson1307 День назад +1

    Sam is 19 his sister is 9

  • @chrisdissanayake6979
    @chrisdissanayake6979 22 часа назад

    Answer: 19 years.
    -----
    Let the age of Sam be Y years.
    Let the age of Sam’s sister be X years.
    Sam is 10 years older than his sister means,
    Y = X + 10 --(1)
    Next year, Sam will be Y+1 years old and Sam’s sister will be X+1
    years old.
    Next year, Sam will be twice as old as his sister means,
    Y+1= 2(X+1)--(2)
    Y= 2X+2-1
    Y=2X+1
    Substituting the above with equation (1),
    X+10= 2X+1
    2X + 1 = X + 10
    X = 9
    Sam’s sister’s age is 9 years.
    Since Sam is 10 years older than his sister, Sam’s age= 9+10=19 years.

  • @Stylux-z1p
    @Stylux-z1p 23 часа назад

    Sister = x
    Sam = x + 10
    next year --> sister = x + 1
    next year --> Sam = x + 10 + 1 = x + 11
    x + 11 = 2(x + 1)
    x + 11 = 2x + 2
    11 - 2 = 2x - x
    9 = x
    Sam x + 10 = 9 + 10 = 19 years at the moment ✅
    Sister = x --> 9 years at the moment
    next year Sam will be 19 + 1 = 20 years
    Sister will be 9 + 1 = 10 years

  • @josephlaura7387
    @josephlaura7387 День назад +1

    19 yrs

  • @wesleyc.4937
    @wesleyc.4937 День назад

    Next year OR one year from today?

  • @narenmenon6906
    @narenmenon6906 14 часов назад

    19 without resorting to linear equations...

  • @panlomito
    @panlomito День назад

    Sis = S and Bro = B so B = S + 10 and B + 1 = 2 x (S + 1)
    (S + 10) + 1 = 2S + 2 -> S = 11 - 2 = 9 yo
    B = 19 yo

  • @adgf1x
    @adgf1x 21 час назад

    now sam is 19 yr.ans(sister now 9yr)

  • @joeamerican2611
    @joeamerican2611 23 часа назад

    It took me maybe 5 seconds to solve it in my head.

    • @DancingPony1966-kp1zr
      @DancingPony1966-kp1zr 22 часа назад

      Congrats.

    • @DancingPony1966-kp1zr
      @DancingPony1966-kp1zr 22 часа назад

      I had no idea how to account for the additional year.

    • @ORRadtech
      @ORRadtech 21 час назад +4

      I understand that this is a math channel and I applaud those who created a formula. But the answer is so simple long calculations are overkill. Common sense and logic are much faster here. With any two siblings the older will only be twice the younger's age once. With a 10 year difference the ages have to be 10 and 20 years of age. In this example that doesn't happen for one year so the elder sib is 19.

    • @gavindeane3670
      @gavindeane3670 18 часов назад +1

      ​@@ORRadtechExactly. Often this form of question constructed a bit differently, e.g. Currently Sam is three times as old as his sister and in 5 years time he will be twice as old. That might require a little bit of algebra, but the way he's written this means it's not an algebra problem at all.

    • @roundtwo3321
      @roundtwo3321 17 часов назад

      @@gavindeane3670
      Sam = 3Sister
      Sam + 5 = 2(Sister + 5)
      SUBSTITUTION:
      3Sister + 5 = 2(Sister + 5)
      3Sister + 5 = 2Sister + 10
      3Sister - 2Sister = 10 - 5
      Sister = 5
      SINCE:
      SAM = 3SISTER
      SAM = 3(5)
      SAM = 15

  • @Meh-j9s
    @Meh-j9s День назад +1

    19

  • @Streetbb77
    @Streetbb77 23 часа назад

    Sam is 19

  • @luillierstephane1463
    @luillierstephane1463 16 часов назад

    He's 19 yo now.

  • @joso5554
    @joso5554 15 часов назад

    Obviously 19.

  • @helenaamaral4659
    @helenaamaral4659 23 часа назад

    19.

  • @roundtwo3321
    @roundtwo3321 23 часа назад

    Sam = Sister + 10
    Sam + 1 = 2(Sister + 1)
    SUBSTITUTION:
    Sister + 10 + 1 = 2(Sister + 1)
    Sister + 11 = 2(Sister + 1)
    Sister + 11 = 2Sister + 2
    11 - 2 = 2Sister - Sister
    9 = Sister
    SINCE:
    SAM = SISTER + 10
    SAM = 9 + 10
    SAM = 19.

    • @josiahndungu4269
      @josiahndungu4269 22 часа назад +1

      @round2 you are the best math teacher.

    • @roundtwo3321
      @roundtwo3321 17 часов назад

      @@josiahndungu4269 You are the best math student.

  • @devonwilson5776
    @devonwilson5776 День назад

    Greetings. Happy Sunday evening to everyone. Blessings. Currently Sam is 19 and his beloved sister is 9 years old.
    Now for the calculations. Let us assume that Sam's sister is X years old. Based on this assumption, Sam would be X+10 years old. Further, one year later the sister would become X+1 years old and Sam would become (X+10+1) years old. Now, we were also told that subsequent to their initial ages of X, and X+10, one year later, next year, when brother and sister would have become
    X+11 and X+1 years old, the brother, Sam's age would be twice the sister's age. That is X+11=2(X+1),
    X+11=2X+2,
    2X-X=11-2,
    X=9. Therefore, Sam's sister is currently, as we speak, 9 years old, the value of X we initially assumed to be her age. Sam's age is (X+10),
    (9+10)=19 years old.

  • @kellahobbs9232
    @kellahobbs9232 День назад +1

    19

  • @richardcroteau4932
    @richardcroteau4932 5 часов назад +1

    19

  • @anthonysaverio5003
    @anthonysaverio5003 5 часов назад

    19