Jack wants to measure the distance between his scout camp and another camp upstream. he can paddle his kayak at a rate of 5 mi/hr in still water, and the rate of the river is 3 mi/hr. if it takes jack 10 hr to paddle to the camp and back, how far is the camp?

Let x be the unknown distance from his scout camp to another camp. The time it takes for him to travel upstream is x / (5 + 3) and downstream x / (5 - 3)

The total time for him to travel forth and back is 10 hr. This may be mathematically expressed as,
              
                                         x/8 + x/2 = 10

Solving for x in this equation gives 16. Thus, the distance to the camp is 16 miles.