Solve for the speed of the current

Question

A boat travels 60 miles downstream in the same time it takes to go 36 miles upstream. The speed of the boat in still water is 15 mph greater than the speed of the current. Find the speed of the current. 

Answer 1

v=d/t  ==>t=v/d

V_b=boat's speed in still water

V_c=river current's speed

(V_b+V_c)/60=(V_b-V_c)/36

Also: V_b=V_c+15

 

If you solve this system of equations you will get speed of the current as well of speed of the boat in still water.