Answer:
C. 1.2x
Explanation:
He pays 1 x for his haircut, and an additional 20% on top of that, or an additional 0.2x. If you write that as an expression, you can simplify it like this:
![1x+0.2x\\1.2x](https://img.qammunity.org/2022/formulas/mathematics/high-school/w521tvd7k4falr4o9kiwiheukvfygsz8tk.png)
You can also work it out by multiplying by 1.2 as stated in answer C. If his haircut costs $10, adding a 20% tip of $2 is the same as multiplying by 1.2.
![10*1.2=12](https://img.qammunity.org/2022/formulas/mathematics/high-school/jb93x5a26g5fcnjoavq9ja22njjlnflmr1.png)