Answer :

iGreen
If you're looking for the point that completes the rectangle, that point is (-4, 1).

See the attachment.
View image iGreen
Let's call our four points A(-2,4),B(4,0),C(2,-3) and D(unknown).

To go from B to C : go 3 units down, 2 units left, hence to go from A to D you do thhe same, and en up at (-2-2,4-3)=(-4,1)