The perimeter of the sandwich is the sum of all its sides, then we have:
[tex]2x^2+8+2x^2+8+2x^2+9+2x^2+9=8x^2+34[/tex]
Therefore the perimeter is:
[tex]8x^2+34[/tex]
The length of the crust is the same as the perimeter of the sandwich; if x=1.2 we have that:
[tex]8(1.2)^2+34=45.52[/tex]
Therefore the length of the crust is 45.52
