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