One F6 Math Question?

triangle BGE is similar to triangle DGF
BE/DF=BG/DG=(3/5)/(4/5)=3/4 --> BG=((3/7)BD
set triangle BEG = x cm^2
x/(x+78)=(BE/AB)*(BG/BD)=(3/5)*(3/7)=9/35
35x=9x+78*9
26x=78*9
x=27 (cm^2) .....Ans: (B)