Textbook exercise I get stuck
"Amy is going to hold a concert at a stadium. The stadium can accommodate 12 000 people. If the price for each ticket is \$160, all the tickets will be sold. For every increase of \$1 in the ticket price, the number of tickets sold will decrease by 50. Let \$p be the price of each ticket and q be the number if tickets sold
(a) express $q$ in terms of $p$, where $p \geq 160$."
Please help!