The length of segment AB is 18 cm. Points D and E divide segment AB into three equal parts.

The length of segment AB is 18 cm. Points D and E divide segment AB into three equal parts. Point O is marked in the middle of segment AB. Find the length of segment OE.

Since the length of the segment AB is 18 cm, and points D and E divide the segment AB into three equal parts, it means that you can find the segment AD. Segment AD = DE = EB.
1) 18: 3 = 6 (cm) – length of segment AD or segment DE.
Point O stands in the middle of the segment AB and divides it in half, and it also divides the segment DE in half.
2) 6: 2 = 3 (cm) – the length of the segment OE. Or 2) 18: 2 – 6 = 3 (cm)
Answer: the length of the segment OE is 3 cm.