SOLUTION: Two trains horizontal one eastbound, one westbound, leave a city at the same time. The speed of the westbound train is 20 miles per hour greater than the speed of the eastbound tra

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Question 169766: Two trains horizontal one eastbound, one westbound, leave a city at the same time. The speed of the westbound train is 20 miles per hour greater than the speed of the eastbound train. After 7 hours, the distance between the westbound train and the eastbound train is 770 miles. Find the speed of the two trains.
Answer by solver91311(24713) About Me  (Show Source):
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If the speed of the faster train is r then the speed of the slower train must be r-20. Since the trains are going in opposite directions, the speed that they are moving relative to each other is the sum of their speeds, or r+%2B+r+-20.

Since distance equals rate times time, or d=rt and the distance is given as 770 miles and the time as 7 hours, we can say:

770=%28r%2Br-20%297

770=%282r-20%297

770=14r-140

14r=910

r+=+910%2F14+=+65

So the westbound (faster) train was going 65 mph, and the eastbound (slower) train was going 20 mph less than that or 45 mph.

Check: The sum of the speeds is 65 + 45 = 110. 7 hours at 110 mph is 770 miles. Answer checks.