Your answer is correct.
Car A is 500metres behind car B.Car A is travelling at 130km/h and car B at 80km/h
How long does it take for car A to catch car B.
Initially I make the unknown time = T
I assume A(130/h)* T =B(80/h)-0.5
Am I thinking in the right direction?
Oh hang on.The difference in speed=50km/h so maybe
speed A-speed B * T=0.5
T=0.01 hours=36 seconds.
That seemed messy.What is the best way?