S(GEF)=EF*GH=8(H is the vertical foot of CD in G direction).

GDE = Germany * high.

S(GFC)=CF*GH

Because DE=EF=FC

So S(GDC)=24.

S(GDC)=CP*DG(P is the vertical foot from C to BD).

s(GBC)= CP * BG = 12(BG = 1/3BD，BG= 1/2BG)

S(BCD)=S(GDC)+S(GBC)=36

S(ABCD)=2S(BCD)=72