D and E are points on side AB and AC of ΔABC. DE is parallel to BC. If AD:DB = 2:3 and area of ΔADE is 4 sq cm, what is the area (in sq cm) of quadrilateral BDEC.
A and B together can do a piece of work in 36 days, B and C together can do it in 24 days. A and C together can do it in 18 days. The three working together can finish the work in