4. There is a contour of a square with a side of 20 cm, it was cut into two groups of equal segments consisting of three and four segments. What is the length of these segments? Find all possible answers.
Answer: 20 cm and 5 cm.

Sketch of the solution.

If each side of the square is cut into at least two segments, there will be 8 segments, and their $4+3=7$. This means one of the segments is equal to the side of the square, and there are three such segments, each 20 cm long. Four segments are obtained by cutting one side of the square into four equal segments, the length of which is 20:4=5(cm).

Criteria. Correct answer, without justification: 1 point.