Math of Finance | Markup & Markdown word problem

Dr. Kate Zhang, Professor at Humber College solving:
Markup & Markdown word problem
Question 4: A retailer purchased a bike for $120. If the expenses were set as 40% of the regular selling price, and the profit was 30% of the regular selling price. What was the regular selling price for the bike?
During a promotion, this bike was marked down 25%. What was the sale price? Also, what was the operating profit or loss during the promotion?

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