A man can row 6 km/hr in still water. If the speed of the current is 2 km/hr he takes 4 hours more in upstream than the downstream. The distance is?

Answer: Option D

Speed of man in still water, x = 6 km/h
Speed of current, y = 2 km/h
Let distance = M
According to question
Upstream time = Downstream time + 4
$$\begin{array}{rl}& \frac{M}{4}=\frac{M}{8}+4\\ & \frac{M}{4}=\frac{M+32}{8}\\ & M=32\\ & \therefore \text{Distance = 32 }km\end{array}$$