You need to attach the figure or we cannot tell what DCB is.
Since AB = AD, is isosceles so the base angles are the same.
Also, the angles of a triangle add up to
Now see if you can continue.
You need to attach the figure or we cannot tell what DCB is.
Since AB = AD, is isosceles so the base angles are the same.
Also, the angles of a triangle add up to
Now see if you can continue.
This diagram is messed up somehow. Every statement you made above has something wrong with it!
Angle x is ABD, not ADB. Angle y is CAD, not BDC. You have AB = AD = AC, not AB = AD = CD. DCB is a straight line segment, not an angle. And though this is not a critical point to make, angle DAB doesn't look anywhere near 20 degrees on your diagram.
-Dan