Bli kvitt tallet under x

$$\begin{array}{llll}\hfill \frac{x}{3}-4& =3& \hfill & \\ \hfill \frac{x}{3}& =3+4& \hfill & \\ \hfill \frac{x}{3}& =7& \hfill & \\ \hfill 3\cdot \frac{x}{3}& =7\cdot 3& \hfill & \\ \hfill \text{<mn>3</mn>}\cdot \frac{x}{\text{<mn>3</mn>}}& =7\cdot 3& \hfill & \\ \hfill x& =21& \hfill & \end{array}$$