The question is: The monthly revenue R from renting x apartments can be modeled by R=2x(900+21x-x^2). If the monthly expense consists of fixed costs totaling $4500, and per unit expense of $150, find:

1. number of rentals that maximize revenue and the profit it produces
2. number of rentals that maximize profit and the profit it produces
3. The monthly apartment rental that maximizes profits.

Thanks