Since the two lines are tangent and they converge at the same point, the two lines are equal in length.
![4x + 7 = 7x - 8 \\ 15 = 3x \\ x = 5](https://img.qammunity.org/2019/formulas/mathematics/middle-school/kl3zbw4xvdrhtsvuuqqnky8n039kvc32f8.png)
First, we set the equations equal to each other. Then, we add 8 to both sides and subtract 4x from both sides. Lastly, we divide both sides by 3. Therefore, x = 5.