Find the value of x for which abcd must be a parallelogram

In a parallelogram, opposite sides are equal and parallel, which means opposite interior angles are equal. 
5x - 3 = 14x - 48
-3 = 9x - 48
45 = 9x
5 = x

5(5) - 3 = 14(5) - 48
22 = 22
The value of x that would make ABCD a parallelogram is x = 5.

Hope this helps =)

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