Rate of boat in still water and rate of current ?

Question

A motorboat travels 102km in 3 hours going upstream. It travels 138km going downstream in the same amount of time. What is the rate of the boat in still water and what is the rate of the current?

Answer 1

b = speed of boat

c = speed of current

 

up: (b - c)3 = 102

down: (b + c)3 = 138

 

3b - 3c = 102

3b + 3c = 138

 

6b = 240

b = 40