Question 911666
In that hour from 4 to 5 train b from Boston has gone 55 miles
from 5 till they meet they have to cover 145 miles
50+55=105 miles per hour
so they will go 105 miles in one hour leaving 40 miles 
 145/105=1.3809523809523809523809523809524 hours 
1 hour 22 minutes 51 seconds
so at 6:23 pm rounded to the nearest minute