Final answer:
Sam will make $60 by mowing the lawn for 4.5 hours, considering his flat fee of $15 and hourly rate of $10.
Step-by-step explanation:
The question involves calculating earnings based on Sam's rate for mowing lawns. Sam charges a flat fee of $15 per lawn and an additional $10 per hour spent mowing. To calculate Sam's total earnings for mowing a lawn for 4.5 hours, we use the following steps:
- Multiply the number of hours worked (4.5) by the hourly rate ($10): 4.5 hours * $10/hour = $45.
- Add the flat fee to the total from step 1: $45 + $15 = $60.
Therefore, if it takes him 4.5 hours to mow the grass at the school, Sam will make $60.