The given equation is
[tex]\frac{2}{7}=\frac{4}{5}+9a[/tex]First, we subtract 4/5 from each side.
[tex]\begin{gathered} \frac{2}{7}-\frac{4}{5}=\frac{4}{5}-\frac{4}{5}+9a \\ 9a=\frac{10-28}{35} \\ 9a=\frac{-18}{35} \end{gathered}[/tex]Then, we divide the equation by 9.
[tex]\begin{gathered} \frac{9a}{9}=\frac{-18}{35\cdot9} \\ a=-\frac{2}{35} \end{gathered}[/tex]