A utility company has the following rate schedule for natural gas usage in a city's business district:
Monthly service charge $8.80 per therm service charge:
1st 25 therms: $0.6686/therm over 25 therms: $0.85870/therm
(a) what is the charge for using 25 therms in one month?
(b) what is the charge for using 45 therms in one month?
(c) construct a function that gives the monthly charge c for x therms of gas