This problem is about linear equations.
To solve it, we need to find the value of x.
![9+9x=10x+2](https://img.qammunity.org/2023/formulas/mathematics/college/7xn47lb48ph6u52qufzqxbnrr45jsk7ju9.png)
First, we need to organize the equation, all terms without variables at the right side, and all terms with variables at the left side
![9x-10x=2-9\text{ }\rightarrow-x=-7](https://img.qammunity.org/2023/formulas/mathematics/college/31bgx61v2vpp7re56pw91zg4jyizx3e1b9.png)
Finally, we multiply the equation by -1 to get the proper answer
![x=7](https://img.qammunity.org/2023/formulas/mathematics/college/zq1e40da7ft5m7vp2pp4z6wy99lb3uqekj.png)
Therefore, the answer is 7.