ANSWER
[tex]\text{ g = }\frac{5}{7}[/tex]EXPLANATION
We want to solve for g in:
[tex]g\text{ - }\frac{3}{7}=\frac{2}{7}[/tex]Collect like terms by moving 3/7 to the right hand side:
[tex]\begin{gathered} g\text{ = }\frac{2}{7}+\frac{3}{7} \\ \Rightarrow\text{ g = }\frac{5}{7} \end{gathered}[/tex]