A clothing business finds there is a linear relationship between the number of shirts, n ,it can sell and the price, p , it can charge per shirt. In particular, historical data shows that 7000 shirts can be sold at a price of $ 79 , while 22000 shirts can be sold at a price of $ 4 . Give a linear equation in the form p = m n + b that gives the price p they can charge for n shirts. Show your work.