Autilities company measures gas consumption by 100 cubic feet, ccf. the company has a 3 step rate schedule for gas consumers. first, there is a minimum charge of $5.00 per month for up to 3 ccf of gas used. then, for the next 6 ccf, the charge is $.75 per ccf. finally after 9 ccf, the charge is $.55 per ccf. represent the cost of g ccf of gas, if g is greater than 9.