If the points (-2, -1), (1, 0), (x, 3) and (1, y) form a parallelogram, findthe values of x and y.

Let the vertices of the parallelogram be A(-2, -1), B(1, 0), C(x, 3) and D(1, y). Since the diagonals of a parallelogram bisect each other the coordinates of the mid-point of AC = coordinates of the mid-point of BD.

We know that the midpoint of a line segment AB with A(x, y) and B(u, v) is ⇒ -2 + x = 2, y = 2
⇒ x = 4, y = 2.