Here is the diagram. Since this lil kid didn't provide it. :p

Hi there!
The answer is A
Hope this helps you.
Good luck! :)
- WeasuLL
PLEASE GIVE BRAINLIEST
Answer:
D. 21
Step-by-step explanation:
In the diagram, O is circumscribed about the quadrilateral ABCD.
We know, that in the quadrilateral ABCD (inscribed inside the circle) the sum of opposite angles is equal to 180 degrees.
Angle A + Angle C = 180 degrees and Angle B + Angle D = 180 degrees.
So, 5x + 75 = 180
or, 5x = 180- 75
or, 5x = 105
or, x = 105/5
or, x = 21
Hope this helps..
Thank you..!!