How to find the slipping point in a "box on box" System

In this educational video, we delve into the fascinating world of friction and forces within a two-block system (the infamous "box on a box problem." Through a step-by-step analysis, we break down the forces acting on the blocks and examine their effects. We introduce the concepts of static and kinetic friction, as well as explore the role of normal forces and gravity in the system. We will create free-body diagrams as well as force summations. With clear explanations and visual aids, we navigate through the equations and substitutions, ultimately deriving the equation for tension. Join us as we unravel the complexities of friction and gain a deeper understanding of forces in this intriguing scenario.
The problem :
A small box rests on top of a larger box. A string is attached to the bottom box. There is friction between both boxes as well as with the floor. What is the maximum Tension that can be oulled on the string before the top box begins to slip? We will solve the problem using only variables.

[@gurpreetkhamba5399]

Thank, cleared up some confusion.

[@nadia-sy8cn]

Perfect