Answer:
Explanation:
Note: Perimeter = sum of all the lengths of the shape. 
In the case of a square, since all the sides are equal. 
This means that if one side = 8x + 4, the perimeter would be 4 times 8x+4 since there are 4 equal sides in a square. 
Perimeter = 4 ( 8x + 4) 
Perimeter = 32x + 16 
We also get told in the question that the perimeter = 80 inches. 
Meaning that: 
32x + 16 = 80 
From here we can solve for x. 
Subtract 16 from both sides:
32x = 80 - 16 
32x = 64 
Divide both sides by 32 to solve for x. 
x = 64/32 = 2