Question

John's electricity bill costs $20.90 per month plus $1.23 per kilowatt hour. How many kilowatt hours can he use and keep his monthly cost no more than $109

Answer 1

71

kilowatt hours can he use and keep his monthly cost no more than $109

Answer 2

71.63 kilowatts hours

Explanation:

We are told in the question:

John's electricity bill costs $20.90 per month plus $1.23 per kilowatt hour.

We are to find, How many kilowatt hours can he use and keep his monthly cost no more than $109.

Step 1

$109 - $20.90

= $88.1

$88.1 is the amount left to spend on killowatts of electricity per hour after removing the normal monthly electricity bill in a month

Step 2

$1.23 = 1kilowatts per hour

$88.1 = y kilowatts per hour

Cross Multiply

= $1.23 × y kilowatts per hour = $88.1 × 1 kilowatts per hour

y kilowatts per hour = $88.1 × 1 kilowatts per hour/ $1.23

= 71.62601626kilowatts hour.

Approximately = 71.63 kilowatts hour

Therefore, John can use 71.63 kilowatts per hour and keep his monthly cost no more than $109