Answer: The missing length is 120 {option C}
Step-by-step explanation: What we have in the question is a triangle placed on top of another triangle and as shown in the attached diagram we can separate them into triangles BFC and GFH.
A close observation shows that line BC is parallel to line GH. Hence we have two similar triangles, and we can determine their similarity ratios as follows;
BF/FC = GF/FH
Similarly BF/BC = GF/GH
We can also express the following ratio
FC/FH = BC/GH
Therefore to calculate the missing side, which is GF, we can use the ratio
FC/FH = FB/FG
30/100 = 36/FG
By cross multiplication we now have 30 (FG) = 100 (36)
30FG = 3600
Divide both sides of the equation by 30
FG = 120
