I can't get the equation for this question, I spent almost 2 hours!! This is all new to me so sorry for any inconveniance.

Here's the question:

A Car rental agency has 24 identical cars. The owner of the agency finds that a price of $10 per day, all the cars can be rented. However for each $1 increase in rental, on of the cars is not rented. What should he carge to maximize income?

Please help and thanks for even taking the time to help this noob.