Answer: Atleast 7
Explanation:
In order to make a profit you have to amke more money than what you spent for supplies. So if each shirt is 10$ then you would have to sell atleast 7 shirts since if you do you will have made 70$, therefore a 10$ profit. If you sell 6 shirts, you make 60$, meaning you gain all your money back, but you do not make a profit.