Answer:
The two sections will be 125cm apart in 2030.
Explanation:
The rate of movement in the San Andreas fault is said to be between 4 and 6 cm a year. I am going to use 5 cm a year.
The fence was built in 2005, so in 2005 the separation was of 0 cm.
2030 is 2030-2005 = 25 years from 2005, so the separation is of 25*5 = 125 cm.
The two sections will be 125cm apart in 2030.