<PRE><B>Question 158839</B>
two trains traveling in different directions one at 55mph and the other at 45mph
they traveled a total of 400 miles how long did it take to go that distance...
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The basic formula is: distance = rate * time
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1st train DATA:
rate = 55 mph ; distance = x miles ; time = d/r = x/55 hrs.
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2nd train DATA:
rate = 45 mph ; distance = (400-x) miles ; time = d/r = (400-x)/45 hrs
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EQUATION:
time = time
x/55 = (400-x)/45
Cross-multiply to get:
45x = 55(400-x)
45x = 55*400 - 55x
100x = 55*400
x = 55*4
x = 220 miles
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time = distance/rate
time = 220 / 55 = 4 hours 
The time is the same for both of the trains.
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Another way to do the problem.
The trains are going away from one another at (45+55) = 100 mph
The time for them to be 400 miles apart is 400/100 = 4 hours.
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Cheers,
Stan H.

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