Word problem with equation

Question

A Tennis ball is thrown into Swimming pool from the top of a tall hotel. The height of the ball from the pool is modeled by

D(t) = -16t2-4t +300 feet, where t is the time, in seconds, after the ball was thrown. How long after the ball was thrown was it 144 feet above the pool?

Answer 1

D(t) -16t^2 -4t +300 = 144

-16t^2 -4t + 156 = 0

16t^2 +4t -156 = 0

4t^2 + t - 39 = 0

(4t +13)(t-3) = 0

t = 3 seconds to reach 144 feet (ignore the negative t)