Answer: At most 5 people
Step-by-step explanation:
Each person costs $3, so x of them cost 3x dollars. The x is a placeholder for some positive whole number.
We could do guess and check to see when 3x = 15 is true, or we could divide both sides by 3
3x = 15
x = 15/3
x = 5
This means 5 attendees will cost $15.