4.25 mph
Speed, distance, and time are related by ...
... speed = distance/time
... distance = speed · time
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If we let x represent the current speed in miles per hour, the number of miles the jet ski goes upstream is ...
... 0.25(60 -x)
The number of miles it drifts downstream is 2 more than that, or ...
... 0.25(60 -x) +2
The speed it drifts downstream is x, and that speed is equal to the distance divided by the time (3.75 hours):
... x = (0.25(60 -x) +2)/3.75
Multiplying by 3.75, we have ...
... 3.75x = 17 - 0.25x
... 4x = 17
... x = 17/4 = 4.25
The rate of the current is 4.25 miles per hour.
