A clothing business finds there is a linear relationship between the number of shirts, n n , it can sell and the price, p p , it can charge per shirt. In particular, historical data shows that 8000 8000 shirts can be sold at a price of $ 81 $ 81 , while 9000 9000 shirts can be sold at a price of $ 73 $ 73 . Write the price p p as a function of the number of shirts sold.