Cecily is on her roof and wants to throw a ball straight up in the air and figure out how long it will take to reach the ground. The function of an object failing to the ground is f(x) =-32x^2+vx+d. In this function, x is time, v is initial (vertical) velocity in feet per second, and d is the initial distance above the ground in feet. If v is positive= velocity upward. If v is negative= downward. I need to know:

a. The function if Cecily releases the ball 40 feet above the ground at a velocity of 64 feet per second.

b. at that rate how long will it take for the ball to hit the ground.

please help