Answer:
![\large\boxed{\large\boxed{41\%}}](https://img.qammunity.org/2021/formulas/business/middle-school/3zev8otsg9m6nrh81hmis25048htnjlnxs.png)
Step-by-step explanation:
You need to assume that the total expenses were equal to the cost of the supplies, i.e. there were not other expenses but the $1,500 for supplies to sell.
The total income or revenue was $3,700.
The percentage of the expenses to the revenue is:
![Percentage=(expenses)/(revenue)* 100\\\\\\ Percentage=(\$1,500)/(\$3,700)* 100=40.5\%\approx41\%](https://img.qammunity.org/2021/formulas/business/middle-school/vzy960cfpowm17b8423m92j3s8wb16fzml.png)