John and Leah want to move the piano in their living room. John pushes from behind the piano with a force of 300\text{ N}300 N300, start text, space, N, end text, and Leah pulls on a rope tied to the front with a force of 100\text{ N}100 N100, start text, space, N, end text. The piano has a mass of 200\text{ kg}200 kg200, start text, space, k, g, end text, and the friction force of the floor and the piano is 140\text{ N}140 N140, start text, space, N, end text. Calculate the acceleration of the piano.

Edit the post so i can see the letters for each answer, and increase the points required so i'd be able to answer it.

Distance covered = speed x timethe distance traveled going against the stream = distance traveled with the stream.therefore it is the speed and the time that are the variables.as he travels the same distance both ways, speed x time is the same for each way.going upstream his speed is 4 kph; going downstream his speed is 6 kph.therefore we have two simultaneous equations: time upstream x 4 = time downstream x 6time upstream + time downstream = 60 minutestherefore we have the equation: time upstream = 6/10 hour, time downstream therefore = 4/10 hour.distance traveled at 4km/hr in 6/10 hour = 24/10 = 2.4km.check: distance traveled at 6km/hr in 4/10 hour = 24/10 = 2.4km.