Question

Car A, moving in a straight line at a constant speed of 20. meters per second, is initially 200 meters behind car B, moving in the same straight line at a constant speed of 15 meters per second. How far must car A travel from this initial position before it catches up with car

Answer 1

First, let's express the movement of Car A and B in terms of their position over time (relative to car B)
For car A: y=20x-200   Car A moves 20 meters every second x, and starts 200 meters behind car B
For Car B: y= 15x      Car B moves 15 meters every second and starts at our basis point

Set the two equations equal to one another to find the time x at which they meet:
20x - 200 = 15x
200 = 5x 
x= 40
At time x=40 seconds, the cars meet. How far will Car A have traveled at this time? 
Car A moves 20 meters every second:
20 x 40 = 800 meters