2. Solve 112 = 112 + 96t - 16t^2. The larger solution is the answer.
3. Solve h = 400 for x. The height is a maximum halfway between these two values of x.
4. h(0) = 50. So the ground is at h = 50 ....? Get the turning point of the parabola. h-coordinate is the max height. Solve h = 50 for t, the larger solution is the time to return to ground.
5. Where is h meant to be measured from?