Answer: 5 yards
Explanation:
1. Look at the vertical parts of the drawing from right to left
2. Notice that the longest vertical part is 11 yards
3. Notice that the other labels vertical part is 6 yards
4. Notice that the third vertical part, the one with the ? is 11 yds - 6 yds since the two shorter vertical parts would make a line as long as the longest vertical part of they were put together. Since this is the case the missing part is 11 yds-6 yds = 5 yds.