The perimeter of a figure is the boundary of its surface, in this case, it is:
[tex]P=(x+1)+x+x+(x+3)+x+(x+1)+(x+3)[/tex]
I will edit the image to help you understand
This is quite improvised but it'll help you to understand how the sides are related.
So, continuing with the calculation:
[tex]\begin{gathered} P=(x+1)+x+x+(x+3)+x+(x+1)+(x+3) \\ \Rightarrow P=x+1+2x+x+3+x+x+1+x+3 \\ \Rightarrow P=7x+8 \end{gathered}[/tex]
So, the answer is: Perimeter = 7x+8
