Answer:
GB = 15
Step-by-step explanation:
DC, EB and FA are the medians of the triangle.
The point G where the medians intersect is the centroid.
On each median the distance from the vertex to the centroid is twice as long as the distance from the centroid to the midpoint, hence
FG = 2GA, that is
5x = 2(x + 9)
5x = 2x + 18 ( subtract 2x from both sides )
3x = 18 ( divide both sides by 3 )
x = 6
Hence
GB = 2x + 3 = (2 × 6) + 3 = 12 + 3 = 15
