Question 304487
A has a 15 minute head start. How far can a go in15 minutes?
40*1/4=10miles
train b is gaining on a at 8 mph

so it will take b r*t=d
t=d/r
t=10/8 to catch up
1 1/4 hour
add 1:15 to 7:35
8:50 train b acatches train a