Work these problem. (See Example.)The Lacledge Gas Company in St. Louis, Missouri in the w...

Work these problem. (See Example.)

The Lacledge Gas Company in St. Louis, Missouri in the winter of 2012–2013 charged customers $21.32 per month plus $1.19071 per therm for the first 30 therms of gas used and $.57903 for each therm above 30.

(a) How much revenue does the company get from a customer who uses exactly 30 therms of gas in a month?

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(b) Find the rule of the function R (x) that gives the company’s monthly revenue from one customer, where x is the number of therms of gas used. (Hint : R (x) is a piecewise- defined function that has a two-part rule, one part for x ≤ 30 and the other for x > 30.)

Example

The energy company New York State Electric and Gas charges each residential customer a basic fee for electricity of $15.11, plus $.0333 per kilowatt hour (kWh).