Finding distance and rate of the current

Answer 1

It seems you left off some info, but here's how to solve this type of problem.

When traveling downstream, the speed of the current is added to the boat's speed in still water. If my boat travels at 5 mph and I go downstream in a current of 2 mph, I'm going to travel 7 mph.

If I turn around, though, I'm only going to travel 5 - 2 = 3 mph upstream.

It seems that you are given times. If it took 7 hours to go upstream in my boat, I went 7(5 - 2) = 35 - 14 = 21 miles.

I bet that the distance was the same both ways. Let me make up a problem.

A boat travels 5 mph in still water. Going downstream, a trip took 3 hours. The same trip took 7 hours going upstream.

Again, d = rt, and the distances are EQUAL.

3(5 + c) = 7(5 - c)

15 + 3c = 35 - 7c

10c = 20

c = 2 mph

3(5 + 2) = 3(7) = 21 miles.

So, our boat went 21 miles each way in a current of 2 mph.

Go.