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 \( 1,000 \) shirts can be sold at a price of \( \$ 30 , \) while \( 3,000 \) shirts can be sold at a price of \( \$ 10 \) . Find a linear equation in the form \(p ( n ) = m n + b\) that gives the price \( p \) they can charge for \( n \) shirts. Because this answer involves an expression that is more complex than a whole number times \( n \) , remember to type in multiplication symbols \( * \) . For example, if you wanted to enter \( \frac { 1 } { 2 } n \) , type this in as 

\( ( 1 / 2 ) ^ { * } n \) . 

\( p ( n ) = \)