Find angle w , x, y and z

• Angles subtended by arc CD: $\angle CAD = 20^\circ$ and $\angle CBD = y^\circ$. Therefore, $y = 20^\circ$.
• Angles subtended by arc AB: $\angle ADB = 64^\circ$ and $\angle ACB = x^\circ$. Therefore, $x = 64^\circ$.
• Angles subtended by arc BC: $\angle BAC = w^\circ$ and $\angle BDC = z^\circ$. Therefore, $w = z$.

The symbol at $\angle BCD$ indicates that $\angle BCD = 90