Cost of Natural Gas In April 2009, Nicor Gas had the following rate schedule for natural g...

Cost of Natural Gas In April 2009, Nicor Gas had the following rate schedule for natural gas usage in singlefamily residences:

(a) What is the charge for using 40 therms in a month?

---

(b) What is the charge for using 150 therms in a month?

---

(c) Develop a model that gives the monthly charge C for x therms of gas.

---

(d) Graph the function found in part (c).