A jet plane traveling at 500mph overtakes a propeller plan traveling at 150mph that had a 2 hour head start. How far from the starting point are the planes

Question

I'm having trouble understanding how to do the format of the equation 

Answer 1

distance for prop plane = 150t, during t hours of travel.

distance for jet plane     = 500(t-2)

 

Set these two distances equal & solve for t, then either distance formula will give the answer.

Assumes all travel in a 'straight line' away from starting point.