SOLUTION: a local commuter train leaves washington at 6 am averaging 36 mph at 7:15 am, a high speed express train leaves the same station traveling on a on a paralel track at 81 mph when w

Hi, 

d = r*t

Let t represent the time the express train travels. 

then (t + 1.25hr) is the time the local commuter travels (1hr and 15min = 1.25hr)

Distance will be the same when the express train catches up to the local commuter***

36mph(t + 1.25hr)= 81mph*t

36*1.25hr = 45mph*t

1 hr = t, the time the express train travels and will catch up to the local commuter



checking our answer

36mph*2.25hr = 81mph*1hr = 81mi