A ball is thrown verically upward from the balcony of an apartment building. The ball falls to the ground the height of the ball, h metres, above the ground after t seconds is given by the function: h(t)= -5t^2+15t+45

I have the factored form or vertex cant remeber which one it is: y=-5(x+2.3)+56.5

I'm having trouble finding how long it takes the ball to reach the max height. and how high the balcony is

any help is appreciated thnks