Question 293141
a 60 mph 8:20
b 80 mph 8:35
a has a head start of 15 minutes which is 1/4 hr.
in 1/4 hr it goes 15 miles
train b is catching up at 20 miles and hr. so it will catch up in 45 minutes
8:35 +0:45=8:80=9:20 am 
We can also write it:
60*(x+1/4)=80x
60x+15=80x
15=20x
15/20=3/4=x
3/4 hr=45 minutes same as above
Train B catches train A at 9:20 am. ANSWER