a long distance trucker traveled 168 mi in one direction dur

a long distance trucker traveled 168 mi in one direction during a snow storm. the return trip in rainy weather was accomplished at double the speed and took 3 hrs less time, find the speed going

Solution

1st leg DATA:
distance = 168 mi ; rate = x mph ; time = 168/x hrs
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Return leg DATA:
distance = 168 mi ; rate = 2x mph ; time = 168/2x = 84/x hrs
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Equation:
time going - return time = 3 hrs
168/x - 84/x = 3
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Multiply thru by x to get:
168 - 84 = 3x
3x = 84
x = 28 mph (speed going)