The height s of a ball (in feet) thrown with an initial velocity of 60 feet per second from an initial height of 6 feet is given as a function of the time t (in seconds) by s(t) = (-16t^2) + 60t + 6

(a) Determine the time at which height is maximum.

(b) What is the maximum height?

NOTE: I have trouble with questions like this all the time. I never know what number(s) to plug into the formula.