Step 1

We have to use analytical geometry property here.

By analytic Geometry

\(\displaystyle\Rightarrow{9}{\left({9}+{12}\right)}={7}{\left({7}+{x}\right)}\)

\(\displaystyle\Rightarrow{189}={49}+{7}{x}\)

\(\displaystyle\Rightarrow{140}={7}{x}\)

\(\displaystyle{x}={\frac{{{140}}}{{{7}}}}={20}\)

Answer: \(\displaystyle={20}\)

We have to use analytical geometry property here.

By analytic Geometry

\(\displaystyle\Rightarrow{9}{\left({9}+{12}\right)}={7}{\left({7}+{x}\right)}\)

\(\displaystyle\Rightarrow{189}={49}+{7}{x}\)

\(\displaystyle\Rightarrow{140}={7}{x}\)

\(\displaystyle{x}={\frac{{{140}}}{{{7}}}}={20}\)

Answer: \(\displaystyle={20}\)