A motorboat takes 5 hours to travel 100mi going upstream. The return trip takes 2 hours going downstream. What is the rate of the boat in still water and what is the rate of the current?

Answer 1

distance = time * speed
Let
b = boat's speed
c = current's speed

5(b-c) = 100
2(b+c) = 100

b-c = 20
b+c = 50

I guess you can take it from there, yes?