Question 444914
Let c = the speed of the current
The 20 mile downstream travel time will be 20/(15+c)
The 10 mile upstream travel time will be 10/(15-c)
Since the times are equal we have
20/(15+c) = 10/(15-c)
Solve for c:
10(15+c) = 20(15-c)
15+c = 30-2c
3c = 15
c = 5
So the rate of the current is 5 mph
Check:
t = 20/(15+5) = 1 hr
t = 10/(15-5) = 1 hr