A square is divided into four congruent rectangles. The perimeter of each of the four congruent rectangles is 25 units. How many units are there in the perimeter of the square?

there are 4 units of 10, so your answer is 4 (10) = 40

Let s = one side of the square

so s/4 = the shorter side of one of the rectangles while s = the longer side of a rectangle

10s/4 = the perimeter of one rectangle so

10s/4 = 25

s = 10

4s = perimeter of the square

4 (10) = 40 = perimeter of the square = your answer