Question

A boat travelled 210 km downsream and back. The trip downstream took 10 hours. The trip back took 70 hours. What is the speed of the boat in still water?

Answer 1

Downstream speed = x + y

10 = 210 / (x + y)

x + y = 21 —————(1)

Upstream speed = x - y

70 = 210 / (x - y)

x-y = 3 —————(2)

from 1 and 2

x = 12 km/hr

hope it helps mate