Question

A theatre company allows a group of 10 people to buy theatre tickets at a price of $28 per person. For each person in excess of 10, the price is decreased by $2 per person for everyone down to a minimum of $10 per person. What number of people will produce the maximum revenue for the theatre company???

Please help. I don't really know how to write out the quadratic equation for this equation. I tried to do revenue=(price)(quantity), but I can't get the right equation at all.

PLEASE HELP PLEASE HELP ME.