A boat went 12 miles upstream in 8 hours. On the return trip downstream it took four hours. What is the speed of the boat and the current

Question

A boat went 12 miles upstream in 8 hours. On the return trip downstream it took four hours. What is the speed of the boat and the current?

Answer 1

Let b = the speed of the boat

Let c = the rate of the current

d = rt

upstream: 12 = 8(b - c)

downstream: 12 = 4(b + c)

12 = 4b + 4c

3 = b + c      3 - c = b

12 = 8b - 8c

12 = 8(3 - c) - 8c

12 = 24 - 8c - 8c

-12 = -16c

.75 mph = c

b = 3 - c

b = 2.25 mph