Westside Energy charges its electric customers a base rate of $7.00 per month, plus 10 per kilowatt-hour (kWh) for the first 300 kWh used and 3 per kWh for all usage over 300 kWh. Suppose a customer uses x kWh of electricity in one mont (a) Express the monthly cost E as a piecewise defined function of x. (Assume is measured in dollars.) E(x)= if 0 x 300 if 300 < x (b) Graph the function E for 0 x 600. 40 E 30 20 10 x O 100 200 300 400 500 600 40 E 30 20 10 100 200 300 400 500 600 40 30 20 10 E E 70 60 50 40 30 20 10 X 100 200 300 400 500 600 X 100 200 300 400 500 600