Answer:
a. v
Explanation:
Given
![3v - 8](https://img.qammunity.org/2021/formulas/mathematics/high-school/xndv4wcracnbccaiv491480vd0n35wow3z.png)
Required
Identify the variable
Literary, variable means things that change in values;
Going by this definition, we have that:
3 -> This is not a variable because its value will always be 3
v -> This is a variable because its value can change once its value changes, the result of the expression will also change
- -> This is not a variable; it is an arithmetic operator to subtract
8 -> This is not a variable because its value will always be 8
Take for instance
![v = 2](https://img.qammunity.org/2021/formulas/mathematics/middle-school/ltjwozielzhbeqhizk205ra7y5vwp4g7ck.png)
![3v - 8 = 3 * 2 - 8 = 6 - 8 = -2](https://img.qammunity.org/2021/formulas/mathematics/high-school/ku3zfn6v3llwums6xq1jxmhp2nh11im5js.png)
When
![v =5](https://img.qammunity.org/2021/formulas/mathematics/high-school/z71wl35j52ynfeb25b8ml3eya1s7gc6ki1.png)
![3v - 8 = 3 * 5 - 8 = 15 - 8 = 7](https://img.qammunity.org/2021/formulas/mathematics/high-school/5wpwllivzie67euftk4d8zstefbbtc47t7.png)
Notice that there's a difference in both results;
This is as a result of v being a variable