SOLUTION: Two trains leave the station at the same time, one heading east and the other west. The eastbound train travels 20 miles per hour faster than the westbound train. If the two tr

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Question 836146: Two trains leave the station at the same time, one heading east and the other west. The eastbound train travels
20
miles per hour faster than the westbound train. If the two trains are
640
miles apart after
4
hours, what is the rate of the eastbound train?
Do not do any rounding.

Found 2 solutions by checkley79, josgarithmetic:
Answer by checkley79(3341) About Me  (Show Source):
You can put this solution on YOUR website!
LET X BE THE SPEED OF THE EAST BOUND TRAIN
LET X-20 BE THE SPEED OF THE WEST BOUND TRAIN
4[X+(X-20)]=640
4[2X-20]=640
8X-80=640
8X=640+80
8X=720
X=720/8
X=90 MPH FOR THE EAST BOUND TRAIN
90-20=70 MPH FOR THE WEST BOUND TRAIN
PROOF:
4[90+70]=640
4*160=640
640=640

Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
Opposite directions, tells you sum of their distances is 640 miles at the given time of 4 hours.

Eastbound train is the FASTER one.
r = rate of the slower train.


________________speed_____________time___________distance
EastFast________r+20______________4__________(____)
WestSlow_________r_______________4___________(____)
Total_____________________________________________640


Formula for uniform travel rate R*T=D gives expressions for the distances.

________________speed_____________time___________distance
EastFast________r+20______________4______________(r+20)*4
WestSlow_________r_______________4________________r*4
Total_____________________________________________640

Total of distances gives equation to solve for r:
highlight%28%28r%2B20%29%2A4%2B4%2Ar=640%29
Once finding r, you can compute r+20.