Question

Find values in x and y for which ABCD must be a parallelogram

Answer 1

If ABDC is a parallelogram, AB is parallel to DC.

So, 4x-18 and x+6 are alternate angles. Which are congruent.

So:

4x-18 = x+6

Solve for x:

4x-x = 6+18

3x = 24

x=24/3

x= 8