A man is crossing a river flowing with velocity of 5 m/s. He reaches a point directly across at a distance of 60 m in 5 sec. His velocity in still water should be 

His velocity in x direction should counter the flow so as to reach the point across, i.e. v_x​=5 m/s

Velocity in y should be such that he reaches 60 m in 5 second, i.e. v_y​=12 m/s

Thus total velocity, v = $\sqrt{{v_x}^2+{v_y}^2}$​=13 m/s