The perimeter of a square follows the equation P = 4a, in which P is the perimeter and a the length of one side. We know the perimeter is P = 76, and the length of one side is a = 3x+4.
P = 4a 76 = 4(3x+4) 76 = 12x + 16
We need to solve for x. Let's subtract 16 from both sides to have the variables on a side and the numbers on a side: 76 - 16 = 12x + 16 - 16 60 = 12x
Now, let's divide both sides by 12 to have the variable x on a side and its value on the other 60 = 12x 60/12 = (12x)/12 5 = x
