ABCD is a parallelogram. Let C′ be a point on AC extended such that the length of AC′=1.2AC. Let D′ be on the segment BD such that the length of BD′=0.9BD. The ratio of the area of the quadrilateral ABC′D′ to the area of the parallelogram ABCD can be written as ab, where a and b are coprime positive integers. What is the value of a+b?

Answer 1

This is a question of Brilliant[dot]org
jishka please ban the IP address of this user. He has posted Brilliant problems earlier,too.