First, lets multiply both sides of the equation by 'a':
[tex]\begin{gathered} a\cdot(g=\frac{1+2a}{a}) \\ \Rightarrow a\cdot g=\frac{1+2a}{a}\cdot a=1+2a \\ \Rightarrow ag=1+2a \end{gathered}[/tex]
Now we have to move all the terms that have the variable 'a' to the left side of the equation:
[tex]\begin{gathered} ag=1+2a \\ \Rightarrow ag-2a=1 \end{gathered}[/tex]
Notice that now we have that 'a' is common factor on the left side, then we can factor it and get the following:
[tex]\begin{gathered} ag-2a=1 \\ \Rightarrow a(g-2)=1 \\ \Rightarrow a=\frac{1}{g-2} \\ \end{gathered}[/tex]
therefore, a=1/(g-2)
