Answer:
Each part is 3.5 inches long.
Explanation:
The ruler has a length of 7-inches, so when you want to split it directly in half, you divide 7/2. This is the number 3.5 inches. On the ruler you can see when looking at the first segment that it goes from 0 inches to half-way between 3 inches and 4 inches, which is 3.5 inches.