Two piers, A and B, are located s km away from each other along a river. A motor boat, with a speed of vkm/hour in still water, is cruising between the two piers. How much time t (in hours) will the m

Two piers, A and B, are located s km away from each other along a river. A motor boat, with a speed of vkm/hour in still water, is cruising between the two piers. How much time t (in hours) will the motorboat need to get from pier A to pier B and back, if the speed of the current is 5km/hour? Find t if: s=105 and v=40