Hello, can you help me with this question

You plan to sell shirt t shirts as a fundraiser. The wholesale company charge up to $10 a shirt for the first 75 shirt. After 75 shirts shirts you purchase, up to 150 shirts, company lowers its price to 7/5 per shirt. After you purchase 150 the price will describe to $5 per shirt. I need to write a function to model this situation.

This is a piece wise function.