Since both shapes are the same,we divide the total perimeter by 2. 80÷2 is 40. Now that we have the perimeter of each individual shape we have to figure out the length of one side. Since all the sides are equal in length there is only 1 shape that has that - a square. A square has 4 sides so we need to divide 40 by 4 (because squares have 4 sides) and that equals to (40÷4) 10cm on each side. Hope I helped!
