Elementary Algebra

Let X represent the length of one side of the square. One side of the equilateral triangle is 6 centimeters longer than the side of the square, which equals X + 6. The perimeter of a triangle is equal to the sum of all its sides. X+ 6 + X + 6 + X + 6 = 3X + 18 The perimeter of a square can be found by using the formula: P = 4s 4 $\times$ X = 4X Since the perimeters are the same, we can set up the following equation: 3X + 18 = 4X 18 = 4X - 3X X = 18 The length of each side of the square is 18.