ABC company charges its customers according to their usage of electricity. One rate it charges commercial user is as follows: a monthly customer charge of $5.00, $0.04973 energy charge per kwh for the first 2,300 kwh, $0.03505 energy charge per kwh in excess of 2,300 kwh, and $0.00048 conservation charge per kwh. (a) Determine the cost function and draw its graph. (b) What is the total and average charge for using 2000 kwh? (c) How many kwh were used if the total charge is $354.26?