HELP ME ASAP!!!

A ball is thrown into the air with an upward velocity of 40 feet per second. Its height, h, in feet after t seconds is given by the function h(t)=-16t^2+40t+10.

A. What is the ball's maximum height?
B. When the ball hits the ground, how many seconds have passed?

Please show your work. I'm in a huge rush to get this done before the end of the school year!!!