Have you had any experience with finding the centre of mass. If you post what you have managed to do so far we will be able to help you progress from this.
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.