The Solution:
Let the number of students in the soccer team be x, and that in the track team be 3x.
There are 8 students in the soccer team. This means that
![x=8](https://img.qammunity.org/2023/formulas/mathematics/high-school/tgo48not5u16c2rv3wd2v4m7geb5bek1jg.png)
We are to write an equation to represent the number of students.
![\text{ Total number of students = 3x + x}](https://img.qammunity.org/2023/formulas/mathematics/college/ld0n4epntqyh7binyrwj67os8ugjs3zzp5.png)
Therefore, the correct answer is 3x + x.