Answer: the rate uphill is 6 mph.
The rate downhill is 10 mph
Explanation:
Let x represent the rate at which the jogger ran uphill.
The jogger runs 4 miles per hour faster downhill than uphill. This means that speed at which the jogger ran downhill is (x + 4) mph
Time = distance/speed
if the jogger can runs 5 miles downhill, then the time taken to run downhill is
5/(x + 4)
At the same time, the jogger runs 3 miles uphill. It means that the time taken to run uphill is
3/x
Since the time is the same, it means that
5/(x + 4) = 3/x
Cross multiplying, it becomes
5 × x = 3(x + 4)
5x = 3x + 12
5x - 3x = 12
2x = 12
x = 12/2
x = 6
The rate downhill is 6 + 4 = 10 mph