Adam earns $75 per week mowing lawns. this can be represented by the function f(x) = 75x. each week he deposits this money into his bank account. at the beginning of january his bank account had a balance of $500 in it. adam also makes a $45 withdrawal each week. the withdrawals from his account can be represented by the function f(x) = 500 - 45x. write a function that can be used to represent his bank balance after n months, including his monthly deposit and withdrawal.