$\Delta$ABC, the medians AD , BE and CF intersect eachother at the point G. If the area of $\Delta$ ABC is 36 sq.cm, then the area of the quadrilateral BDGF is equal to

A and B are friends and their ages differ by 2 years. A's father D is twice as old as A and B is twice as old as his sister C. The age of D and C differ by 40 years. Find the age of A (A > B)

Jaydeep purchased 25 kg of rice at the rate of Rs. 16.58 per kg and 35 kg of rice at the rate of Rs. 24.50 per kg. He mixed the two and sold the mixture. At what price per kg did he sell the mixture to make 25%. Profit ?