Answer:
C.
![3(4+n)=n+18](https://img.qammunity.org/2020/formulas/mathematics/high-school/n9b253548sz93en4bshz3g5ijd0dmxxsg7.png)
![n=3](https://img.qammunity.org/2020/formulas/mathematics/high-school/bniwkmpbbnwkxheuhsxe8uo03pkym9d5cm.png)
Explanation:
Let n represent the number.
The sum of 4 and a number would be
.
Three multiplied by the sum of 4 and a number would be
.
18 more than the number would be
.
To solve for the number, we will equate both expression as:
![3(4+n)=n+18](https://img.qammunity.org/2020/formulas/mathematics/high-school/n9b253548sz93en4bshz3g5ijd0dmxxsg7.png)
Therefore, our required equation would be
.
Let us solve for n.
![3*4+3*n=n+18](https://img.qammunity.org/2020/formulas/mathematics/high-school/sondxy2odl7rt9qn7jirgrgmprdajxnxtx.png)
![12+3n=n+18](https://img.qammunity.org/2020/formulas/mathematics/high-school/1bep88rk4a27vk3f6uw8uehrny7qb713r9.png)
![12-12+3n=n+18-12](https://img.qammunity.org/2020/formulas/mathematics/high-school/is7x74biimpmvcr4l9e61haqm7omemxjtr.png)
Therefore, the number is 3.