Question 1095472
Ming's boat goes 20 mph in still water. It travels 75 miles upstream and back in a total time of 8 hours. what is the speed of the current?
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c = current
75/(20-c) + 75/(20+c) = 8
75*(20-c) + 75*(c+20) = 8(400 - c^2) = 3200 - 8c^2
3000 = 3200 - 8c^2
8c^2 = 200
c^2 = 25

c = 5 mi/hr
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If you mean it's 75 miles round-trip, do it the same way.