Incorrect. By adding 9, you end up with $\displaystyle\frac{{1}}{{3}}{x}+{18}\usepackage{cmbright}\Huge\$ , which does not isolate the variable. Dividing the whole expression by three gives you a result of $\displaystyle\frac{{1}}{{9}}{x}+{6}\usepackage{cmbright}\Huge\$ . To isolate the variable, you need to perform the inverse of each operation. The inverse of +9 is -9, so you need to subtract 9, which willl result in $\displaystyle\frac{{1}}{{3}}{x}\usepackage{cmbright}\Huge\$ . The inverse of dividing by 3 is multiplying by 3, so multiplying $\displaystyle\frac{{1}}{{3}}{x}\usepackage{cmbright}\Huge\$ by 3 will give you x. So the correct method is to subtract 9, and then multiply by 3.