Question

Roberto left his parent's house at 11 A.M. traveling at an average rate of 30 mph. His parents left their house at 12 P.M. traveling at an average rate of 45 mph going the same way as Roberto so that they could catch up to him. After how many hours will it take Roberto's parents to catch up to him?
How do I set up this equation?

Answer 1

As the movement, it is not accelerated then 

Xr = 30 T
Xp = 45(t-1)

they both will meet when x is the same, so

30T = 45T - 45
T = 3 
they both will meet 3 hours after Roberto leaves, at 2 pm