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.
First, we have to find the values of the variables. AB = DC, so 25 = 5x. 25/5 = 5, so x = 5 AD = BC, so 2y = y + 5. Subtract y from both sides: y = 5 Now we know both x and y equal 5. AB and BC are adjacent, so we can use those two. AB = 25 BC = 2(5) = 10 Option B is the correct answer
