What is the equation process to this question?

Evaluate the function to answer the question.

The height h, in feet, of a ball that is released 4 ft above the ground with an initial upward velocity of 80 ft/s is a function of the time t, in seconds, the ball is in the air and is given by the following.

h(t) = −16t^2 + 80t + 4, 0 ≤ t ≤ 5.04

(a) Find the height of the ball (in feet) above the ground 2 s after its released.

(b) Find the height of the ball (in feet) above the ground 4 s after its released.