You have the following information:
- John bought 15 cookies
- John ate 3 of the 15 cookies
In order to calculate the percentage associated to the 3 cookies John ate, respect to the total cookies, you proceed as follow:
![(3)/(15)(100)=(300)/(15)=20](https://img.qammunity.org/2023/formulas/mathematics/college/dxnlvs74ccob6kbwrf327g10bcw3b90ws2.png)
Hence, John ate 30% of the total number of cookies.