Answer:
You need to paint 9 faces to earn $15 in profit.
Step-by-step explanation:
Given : You buy painting supplies for $12, and you charge $3 per person to paint faces.
To find : How many faces will you need to paint to earn $15 in profit?
Solution :
Let x represent the number of faces painted.
According to question,

Solving equation,




Therefore, You need to paint 9 faces to earn $15 in profit.