If AD is connected, the area of triangle ABC =3* the area of triangle ADC = the area of triangle ABD *3/2.

BD:DC is 2: 1, then AB is divided into four parts, so 3AE=BE.

Then triangle ABD area =4* triangle ADE area = triangle BDE area *4/3.

Triangle ADC area+triangle ADE area

= area of triangle ABC /3+ area of triangle ABD /4

= triangular abdominal area /2+ triangular abdominal area /4

= area of triangle ABD *3/4

BDE area of triangle