A real estate office manages 50 apartments in a downtown building. When the rent is $900 per month, all the units are occupied. For every $25 increase in rent, one unit becomes vacant. On average, all units require $75 in maintenance and repairs each month. How much rent should the real estate office charge to maximize profits?
I did it like this: let x represents the number of increase or decrease in rent and apartment, then I got the equation:
but I know I must did something wrong... Can someone help me with this?