Question

It takes Tom five hours to travel 20 miles downstream. It takes him eight hours to travel the same distance back up stream. How fast is the boat? How fast is the current?

Answer 1

speed of boat --- x mph
speed of current --- y mph

5(x+y) = 20
x+y = 4

8(x-y) = 20
x-y = 2.5

add them:
2x = 6.5
x = 3.25
then y = .75

state the conclusions.

Answer 2

v+c = 20/5 = 4
v-c = 20/8 = 2.5
----------------------add
2 v = 6.5

v = 3.25

c = 4 - 3.25 = .75