[tex]\begin{gathered} \frac{1}{2}(px-2)=9 \\ \frac{px-2}{2}=9 \\ \text{Cross multiply and you have;} \\ px-2=18 \\ \text{Add 2 to both sides of the equation} \\ px-2+2=18+2 \\ px=20 \\ \text{Divide both sides by p} \\ \frac{px}{p}=\frac{20}{p} \\ x=\frac{20}{p} \end{gathered}[/tex]
The answer is;
x = 20/p