How do I solve this?

Question

A ball is thrown directly upward from a height of 30 feet with an initial velocity of 64 feet per second. the equation h=-16t^2+64t+30 gives the height after t seconds. how long does it take for the ball to reach it's maximum height?

Answer 1

Maximum height occurs at the vertex of the height-vs.-time parabola, which is at

 

t = -64/[2(-16)] seconds = ? seconds