You make and sell face masks for $10 each. Each mask requires $4.50 worth of fabric. You pay $12.99 total for all your masks to have elastic added to them. Your expenses (in dollars) are given by the expression 4.5m + 12.99, where m is the number of masks you make. Your income is given by the expression 10s, where s is the number of masks you sell. Your profit is equal to the difference of your income and your expenses.