ANSWER: FG = 69
FG = FK + KG
KG = 1/2(FK)
FK = 46
RULE: When it comes to centroids, the longer section of the line is always 2/3 of the entire line (+ the shorter section of the line is always 1/3). This means that the shorter section of the line is HALF of the longer section of the line.
FG = FK + KG
FG = 46 + 46/2
FG = 46 + 23
FG = 69
CHECK:
FK = 2/3(FG)
46 = 2*69/3
46 = 138/3
46 = 46 ✔️
or
KG = 1/3(FG)
1/2(FK) = 1/3(FG)
46/2 = 69/3
23 = 23 ✔️