Pass through point C, make a straight line parallel to AD, and cross BF to G. Because CG is parallel to AC, BC: BD = BG: BF.

And because CG is parallel to AD, GE=EF.

So from the above two relationships, be: ef = 5: 1.

Because BC=2CD, triangle ABC = 200/3cm2.

Because AE=EC, triangle ABE= triangle CBE = 100/3cm2.

And because be: ef = 5: 1, the triangle AEF=20/3 square centimeters.