She walks 26m from flag 14 to flag 1. She fixes the flag and walks back to pick up the next flag, another 26m. She picks up flag 27 and walks 26m to put it in place. Then she returns to flag 14 to pick up flag 2. So she has walked 104m to place flags 1 and 27.
The next two flags would be 2 and 26 which are both 24m away so she has to cover 96m to place these. The series is 104+96+88 and so on until she has only 8m to walk to fix flags 13 and 15. She then puts flag 14 in place, picks up her things and leaves.
So she walks half the distance carrying flags to their destinations and half the distance empty-handed walking back to flag 14 after placing the flags.
Does that make sense?