ANSWER:
![d_n=4n+16_{}](https://img.qammunity.org/2023/formulas/mathematics/college/g238cytdbgqv4u5acp22jk6zk32mnufakz.png)
Explanation:
If n is the number of days that pass.
So each day Sam gets 4 more, which means that he would multiply the number of days by 4, before adding that number to the original number of pennies, which was 16.
Therefore, the equation would be:
![d_n=4n+16_{}](https://img.qammunity.org/2023/formulas/mathematics/college/g238cytdbgqv4u5acp22jk6zk32mnufakz.png)