A baseball is thrown off a building 320 feet high at an initial upward speed of

A baseball is thrown off a building 320 feet high at an initial upward speed of 80 feet per second: the height of the baseball relative to the ground is modeled by F( X) = -16T^2 + 80T + 320. How long does it take the baseball to reach its highest point? 4.2 seconds
4 seconds
7.6 seconds
2.5 seconds
5.2 seconds