Question 99069
Let t=time after Train A leaves until the are at the same point
distance(d)=rate(r) times time(t) or d=rt; r=d/t and t=d/r

When train A leaves, train B has already travelled 172*2.25 or 387 mi

Now when the distance train A travels plus the distance train B travels equals 2823 mi the two trains will be at the same point 

Distance train B travels =387+172t

Distance train A travels 172t

So our equation to solve is:

387+172t+172t=2823 subtract 387 from both sides 

387-387+344t=2823-387  combine like terms

344t=2436  divide both sides by 344

t=7.081************* hrs--------time after Train A leaves until the are at the same point

Ck
172*7.081*********+172*7.081**********+387=2823

1218+1218+387=2823
2823=2823


Hope this helps----ptaylor