Three vertices of parallelogram WXYZ are W(3,1), X(2,7),and Z(4,0). How do I find the coordinates of vertex Y?

Some of the properties of a parallelogram:
a) Opposite sides are parallel.
b) Opposite sides are congruent.
c) Opposite angles are congruent.
d) The diagonals bisect each other, #=># the two diagonals have the same midpoint.

The Midpoint Formula: The midpoint of two points, #(x_1, y_1)# and #(x_2, y2)# is the point M found by the following formula :

#M=((x_1+x_2)/2, (y_1+y_2)/2)#

First, let #XZ and WY# be the two diagonals,
#=> XZ and WY# have the same midpoint,

#=> (2+4)/2=(3+x)/2, => x=3#
#=> (7+0)/2=(1+y)/2, => y=6#

Hence, the first coordinates of vertex #Y# are #(3,6)#

Then, let #XW and YZ# be the two diagonals,
# => XW and YZ# have the same midpoint.

#=> (2+3)/2=(x+4)/2, => x=1#
#=> (7+1)/2=(y+0)/2, => y=8#

So the second coordinates for vertex Y are #(1,8)#

Hence, the two possible coordinates for vertex Y are #(3,6) and (1,8)#