The sum of the measures of the exterior angles of a regular 9-gon, one at each vertex, is the sum of the measures of the exterior angles of a regular 7-gon, one at each vertex.

I dont know try this answer vertex=7

So if we imagine a rectangle in our head, we know that there will be coresponding heights(y) and coresponding widths(x) we look at the y values given (x,y) -3,-3,2 the other y value must be 2 the answer is either B or D look at the x values -3,7,7 the x value must be -3 the answer is x=-3 y=2 (-3,2) the answer is D (-3,2)