Use the distributive property on the left side to simplify:

$\displaystyle{12}{x}-{3}+{9}-{x}={2}{x}+{8}+{9}{x}\usepackage{cmbright}\Huge\$

Combine like terms on both sides: $\displaystyle{11}{x}+{6}={11}{x}+{8}\usepackage{cmbright}\Huge\$

Subtract $\displaystyle{11}{x}\usepackage{cmbright}\Huge\$ from both sides: $\displaystyle{6}={8}\usepackage{cmbright}\Huge\$

This is false, and it means that this equation has no solution.