A boat going upstream (against the current) travels in a 105 miles in 15 hours. It takes the same boat 7.5 hours to make the same trip when it is traveling back downstream (with the current).

Question

What is the speed of the boat in still water and what is the speed of the current of the river?

Answer 1

105 = (R-S)*15 ----> R-S = 7

105 = (R+S)*7.5 ---> R+S = 14

2R = 21

R = 21/2 = 10.5

10.5 - S = 7

-S = -3.5

S = 3.5

and R+S = 10.5 + 3.5 = 14

Speed of the boat is 10.5

Speed of the current is 3.5