heey guys how would I do these

1. The revenue from a company's product is given by R=180m+42m^2-m^3 where m is the output (per unit of time). Determine the output that will give maximum revenue.

2. An objet is projected into the air. The height of the object after t seconds is given by h=60t-5t^2

(I) what is the maximum height the object reaches?

(ii) how long after reaching the maximum height is the object 100m above its starting level?

for 2i I got 180m? is it right? dunno the rest :(

thank you all!