I need help with a Math Equation

Question

a toy rocket is launched vertically upward from ground level with an initial velocity of 80 feet per second. its height after t seconds is given by the equation h(t)= -16t + 48t. how long before the rocket hits the ground?

Answer 1

0 = -16t^2 + 48t

0 = -16t(t - 3)

-16t = 0 ---> t = 0

t-3 = 0 ---> t=3

3 seconds