Find the value of x for which abcd must be a parallelogram 3x 4x-5

Let's first denote the intersection point of diagonals with O. In this parallelogram, we can observe that ΔAOB is congruent to ΔCOD because of AB=CD and the angles ∠BAO and ∠OCD are equal (They are alternate angles). According to the rule of congruency, 3x=4x-5 and x=5

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