As given that the perimeter(P) is 28x-11 inches.
And the sides are:
(8x+2), (8x+2), (5x+12)
Let the another side as L:
So the perimeter of the given is calculate is:
[tex]\begin{gathered} P=(8x+2)+(8x+2)+(5x+12)+L \\ 28x-11=21x+16+L \\ L=28x-21x-11-16 \\ L=7x-27 \end{gathered}[/tex]So the missing side have length 7x-27 inches.
