Pls help the following question;

The centroid (centre) of an object is the average of its x and y coordinates. A pentagonal object has vertices as follows;

Vertex A B C D E

Coordinates (1,2) (4,2) (5,5) (4,6) (2,5)

a) Calculate the centroid of the pentagon

b) Find M, the 3x3 matrix that scales the pentagon by a scale factor of 2.5 about ist centroid

Thank you very much.