we have the following:
[tex]p=2\cdot w+2\cdot l[/tex]
therefore, replacing:
[tex]\begin{gathered} p=2\cdot(x+3+x)+2\cdot(x+3+x+3+x) \\ p=2\cdot(2x+3)+2\cdot(3x+6) \\ p=4x+6+6x+12 \\ p=10x+18 \end{gathered}[/tex]
the answer is, the perimeter is 10x + 8
