Hi there!
First, let's figure out how long one part would be.
WORK:
3 = 9x
x = 3/9 or 1/3 of a unit
Next, we can multiply one part by 2 to figure out how long two parts would be.
WORK:
1/3 x 2
2/3
ANSWER:
2 parts of a segment is 2/3 of a unit
Hope this helps!! :)
If there's anything else that I can help you with, please let me know!