Use matrix method to solve 2+y=3,x+2y=9

What are the following algebraic equations. you need to post those if you want the answer

“exterior angles of triangles. an exterior (or external) angle is the angle between one side of a triangle and the extension of an adjacent side. try this drag the orange dots on any vertex to reshape the triangle.” look to get to the answer i explained what it means and other things i hope it you .