SOLUTION: An express train travels 90 km per hour from A to B. A local train takes 2.5 hours longer to travel the same distance at 50 km per hour. How far apart are A and B? I know the an

Algebra ->  Equations -> SOLUTION: An express train travels 90 km per hour from A to B. A local train takes 2.5 hours longer to travel the same distance at 50 km per hour. How far apart are A and B? I know the an      Log On


   



Question 229669: An express train travels 90 km per hour from A to B. A local train takes 2.5 hours longer to travel the same distance at 50 km per hour. How far apart are A and B? I know the answer is 281.25 but how is the problem set up?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
An express train travels 90 km per hour from A to B.
A local train takes 2.5 hours longer to travel the same distance at 50 km per hour.
How far apart are A and B?
:
Let d = dist from A to B
;
Write a time equation: Time = dist%2Fspeed
:
Slow train time = Fast train time + 2.5 hrs
d%2F50 = d%2F90 + 2.5
:
Multiply equation by 450 to get rid of the denominators, results
9d = 5d + 2.5(450)
9d - 5d = 1125
4d = 1125
d = 1125%2F4
d = 281.25