Tom wants to open a store that sells hats. He thinks he can sell them for $20 each. He estimates his monthly expenses to be $3,000, and it will cost him $8 for each hat. Tom wants to analyze his estimated revenues and expenses to see how many hats he would need to sell each month in order to break even. He uses x to represent the number of hats and y to represent the total dollars. Write a function that represents Tom's expenses each month.