Can anybody help me please ?

Jack is standing on the roof of his house in kicked a rubber ball in the air for it to land on the ground for his dog Henry to fetch. The ball is launched into the air from a height of 12 feet at time t=0. The function that models the situation is h(f) = -2t^2 + 10t +12, where T is measured in seconds and H is the height in feet

When will the ball hit the ground

And how did you get the answer ?