Solve the all parts of given problem:
Problem: A projectile is launch from a high plateau so that it just clears a cliff's edge and falls to the valley floor below. A person standing on the valley floor sees that is takes 3.5 s from the moment it passes the cliff's edge to when it strikes the valley floor, and that it strikes the ground 150m from the edge of the cliff with an impact speed of 95 m/s.
Part A: How tall is the cliff (h)?
Part B: At what initial velocity (magnitude and direction) was the projectile launched?
Part C: How far from the cliff's edge was the projectile launched (R)?
Part D: How long was the projectile in the air from its initial launch?
I need help to find how long the projectile in the air from its initial launch.