Hey there!
To get this perimeter, we need to have all the side lengths. In this picture, all side lengths but 2 is given. Thus, we have to find the two missing side lengths.
[tex]20-7=13[/tex]
[tex]18-12=6[/tex]
Thus, the two missing side lengths are 13 and 6.
Now, let's add all the side lengths.
[tex]20+12+18+7+13+6[/tex]
[tex]=\boxed{76}[/tex]
The perimeter is 76 inches, which is answer choice D.
Hope this helps! :)
