The cost of electricity in a certain city is $0.08 for each of the first 300kWh (kilowatt-hours) and $0.13 for each kilowatt-hour over 300kWh. Find the number of kilowatt-hours used by a family with a $51.95 electric bill.

Step-by-step explanation:

0.08*300 + 0.13x = 51.95

Multiply thru by 100 to get:

8*300 + 13x = 5195

13x = 5195-2400

13x = 2,795

x = 215 hours

515

Step-by-step explanation:

0.08×300 = 24

24 + 0.13(x-300) = 51.95

0.13(x-300) = 27.95

x-300 = 215

x = 515 kWhours