AB = 4x
DC = x + 9
AD = 6
BC = 2y
Quadrilateral ABCD is a parallelogram if both pairs of opposite sides are congruent. Show that quadrilateral ABCD is a parallelogram by finding the lengths of the opposite side pairs.
A) 6, 3
B) 9, 6
C) 12, 6
D) 12, 9