###Human: Grover bought 3 boxes of face masks. He plans to sell them for $0.50 each. If each box has 20 face masks, and he bought the 3 boxes for $15, how much will be his total profit?, ### Assistant: Grover will earn $0.50 x 20 = $10 for each box.
So, he will earn $10 x 3 = $30 after selling all the face masks.
Therefore, his total profit will be $30 - $15 = $15. 
 So the answer is :  15