Answer:
20.05 kilowatt-hour
Step-by-step explanation:
Total electric bill = $84.21
Charges per kilowatt-hour = $0.14
Days in April = 30 days
Number of hours = x
Total electric bill = Charges per kilowatt-hour × Days in April × Number of hours
84.21 = 0.14 * 30 * x
84.21 = 4.2 * x
84.21 = 4.2x
Divide both sides by 4.2
x = 84.21 / 4.2
= 20.05
x = 20.05 kilowatt-hour
Therefore, Luke use 20.05 kilowatt-hour per day during the month of April