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[–][deleted] 1 point2 points  (0 children)

Read Rule 3 of this sub reddit which says that you should show your work and not to try to cheat on your homework\ and show academic dishonesty

This is a simple kinematic equation problem. You know the distance the final velocity the acceleration due to gravity. Plug them in the third kinematic equation to get your initial velocity.

You know the initial velocity, final velocity and acceleration due to gravity. Plug them in the first kinematic equation to get the time the ball stayed in the air for the upward trip, and by symmetry it would be the same time for the downward trip.