Residents of the town of Maple Grove who are connected to the municipal water supply are billed a fixed amount yearly plus a charge for each cubic foot of water used. A household using 1000 cubic feet was billed $72, while one using 1600 cubic feet was billed $108.

(a) What is the exact charge per cubic foot?

(b) Write an exact equation for C, the total cost, of a resident's water as a function of w, cubic feet of water used.

(c) How many cubic feet of water used would lead to a bill of $135? Give your answer to the nearest cubic foot.

ok, i just need some help with this problem....last time i did it, it didn't seem to work right...any help is greatly appreciated...thanks

mathlete