Given:
We're a given figure ABCD
∠ADB = x - 30
∠DBC = -9 - 6x
To find:
The value of x for which ABCD must be a parallelogram.
Step-by-step solution:
For ABCD to be a parallelogram, Its Alternate angles (Z - angles) must be equal.
Thus,
∠ADB = ∠DBC
x - 30 = -9 - 6x
7x = 21
x = 3
Final answer:
For ABCD to be a parallelogram, The value of x should be equal to 3.