Respuesta :

D is on the same point on the x-axis as A and the same point on the y-axis as C, therefore the coordinate for D is (3,3).
B is on the same point on the x-axis as C and the same point on the y-axis as A, therefore the coordinate for B is (9,11).

Hope you understand, I'm not amazing at explaining things :)
Opposite sides of a rectangle are equal and parallel, so B is (9, 11) and D is (3, 3).

Hope this helps!