Need help on this one

The value of x is 21 ft.
Solution:
The given image is a triangle.
In ΔABC, GH is the mid-segment.
Given GB = 21 ft and AG = x ft
To find the value of x:
Since GH is the mid-segment of triangle ABC,
G is the mid point of the line segment AB.
By mid point definition,
AG = GB
AG = 21 ft
x = 21 ft
Option B is the correct answer.
The value of x is 21 ft.