Final answer:
To earn at least $120 for camp at a rate of $7.50 per lawn, one must mow at least 17 lawns, as you cannot mow a fraction of a lawn.
Step-by-step explanation:
To determine how many lawns must be mowed to earn at least $120 when you are paid $7.50 for each lawn, you can use simple division. First, divide the total amount needed, $120, by the amount earned per lawn, $7.50. This will give you the number of lawns that need to be mowed to meet your goal.
Calculation: $120 ÷ $7.50 = 16 lawns
Hence, you must mow at least 16 lawns to earn enough money to pay for camp. However, since you cannot mow a fraction of a lawn, you would need to mow 17 lawns to ensure you earn at least $120.