Final answer:
To earn the same amount as before raising her rate, Nadia would need to work 35 hours at her new rate of $8.25 per hour.
Step-by-step explanation:
Nadia initially charges $7.50 per hour for babysitting and works 18.50 hours the first week and 20 hours the second week of the month. To calculate her earnings for the first two weeks, we add her hours for both weeks and multiply by her hourly rate:
Week 1: 18.50 hours x $7.50/hour = $138.75
Week 2: 20 hours x $7.50/hour = $150.00
Total earnings = $138.75 + $150.00 = $288.75
After raising her rate by $0.75, her new hourly rate is $7.50 + $0.75 = $8.25 per hour. To find out how many hours she needs to work to earn the same amount at her new rate, we divide her total earnings by the new rate:
Total earnings / New rate per hour = $288.75 / $8.25/hour = 35 hours
Nadia would need to work 35 hours at her new rate to earn the same amount as she did in the first two weeks of the month.