A coin, thrown upward at time $t=0$ from the window of an office in the Empire State Building, has height in feet above the ground $t$ seconds later given by

$h(t)=-16t^2+64t+720=-16(t-9)(t+5)$

$($a$)$ From what height is the coin thrown?

The coin is thrown from feet.

$($b$)$ At what time does the coin reach the ground?

The coin reaches the ground seconds after it was thrown.