Let's recall that perimeter of a polygon is the result of adding up the length all its sides. We know in advance that the perimeter of the polygon is 131 ft.
In our case, the length of this polygon are:
x + 6
x + 1
2x + 3
2x - 2
x - 2
4x - 7
Then, the perimeter is:
x + 6 + x + 1 + 2x + 3 + 2x - 2 + x - 2 + 4x - 7
11x - 1
Now we can replace, as follows:
11x - 1 = 131
11x = 132
Dividing by 11 at both sides:
11x/11 = 132/11
x = 12
We found that the value of x is 12