You sell lemonade for 50 cents per glass. you invested $2.00 in the ingredients. write a formula that gives the profit in dollars p = p(n) as a function of the number n of glasses you sell.

Each glass you sell makes you gain 0.5 dollars. So, if you sell glasses, you will gain dollars.

We also take into account that you spend 2 dollars at the beginning, which we must subtract from the future gains:

Since profit is gain minus expenses.