The Question is :
A uniform lamina with mass/unit area 0.12grams/cm2 consists of a square of
side 80cm, with one corner at the origin O(0,0) and other corners at B(80,0),
C(80,80) and D(0,80). A triangle of material has been removed from one corner by cutting a straight line from E(50,0) to F(80,40), and a particle of mass 0.5kg is attached at C. Find the coordinates of the centre of mass.