Answer :
[tex]\frac{a}{(2+6z)}[/tex]
Explanation
[tex]a=2x+6xz[/tex]Step 1
apply common factor
[tex]\begin{gathered} a=2x+6xz \\ a=x(2+6z) \\ \end{gathered}[/tex]Step 2
divide both sides by (2+6z)
[tex]\begin{gathered} a=x(2+6z) \\ \frac{a}{(2+6z)}=x \\ x=\frac{a}{(2+6z)} \end{gathered}[/tex]I hope this helps you