Final answer:
The babysitter would need to work for 3 hours at the rate of $7.50 per hour to earn a total of $22.50.
Step-by-step explanation:
To calculate the number of hours the babysitter would need to work to earn $22.50 at the rate of $7.50 an hour, we divide the total amount earned by the hourly rate. This is a basic division problem in mathematics.
The formula to find the number of hours worked is:
Hours Worked = Total Amount Earned ÷ Hourly Rate
Using this formula:
Hours Worked = $22.50 ÷ $7.50
Hours Worked = 3 hours
Therefore, the babysitter would need to work for 3 hours to earn $22.50.