We are given:

\(\displaystyle{2}{\left({y}-{4}\right)}\leftarrow{18}\)

Divide both sides by 2:

\(\displaystyle{\frac{{{2}{\left({y}-{4}\right)}}}{{{2}}}}\leftarrow{\frac{{{18}}}{{{2}}}}\)

\(\displaystyle{y}-{4}\leftarrow{9}\)

Add 4 to both sises:

\(\displaystyle{y}-{4}+{4}\leftarrow{9}+{4}\)

\(\displaystyle{y}\leftarrow{5}\)

\(\displaystyle{2}{\left({y}-{4}\right)}\leftarrow{18}\)

Divide both sides by 2:

\(\displaystyle{\frac{{{2}{\left({y}-{4}\right)}}}{{{2}}}}\leftarrow{\frac{{{18}}}{{{2}}}}\)

\(\displaystyle{y}-{4}\leftarrow{9}\)

Add 4 to both sises:

\(\displaystyle{y}-{4}+{4}\leftarrow{9}+{4}\)

\(\displaystyle{y}\leftarrow{5}\)