Let's begin by listing out the information given to us:
[tex]\begin{gathered} 9x+12=7x \\ We\text{ will solve for x by putting like terms together. We have:} \\ \text{Subtract 7x from both sides:} \\ 9x-7x+12=7x_{}-7x \\ 2x+12=0 \\ \text{Subtract 12 from both sides:} \\ 2x+12-12=0-12 \\ 2x=-12 \\ \text{Divide both sides by 2, we have:} \\ \frac{2x}{2}=-\frac{12}{2} \\ x=-6 \end{gathered}[/tex]