Question 328962
Use D = rt.

Let d = speed of the river's current

GOING TRIP:

rate = s + d

time = 2 hours

distance = 8 miles

==================

RETURN TRIP:

rate = s - d

time = 4 hours

distance = 8 miles

===================

2(s + d) = 8
4(s - d) = 8

2s + 2d = 8
4s - 4d = 8

4s = 4d + 8

s = (4d + 8)/4

s = d + 2

2(d + 2) + 2d = 8

2d + 4 + 2d = 8

4d + 4 = 8

4d = 8 - 4

4d = 4

d = 4/4

d = 1