In ∆ABC,
∵ ∠A = ∠B | Given
∴ ∠CAB = ∠CBA (= 85°)
| Angles opposite to equal sides of a triangle are equal
Also, x + ∠CAB + ∠CBA = 180°
| Angle sum property of a triangle
⇒ x + 85° + 85° = 180°
⇒ x = 10°
In ∆BCD,
∵ BD = CD
∴ x = z = 10°
| Angles opposite to equal sides of a triangle are equal
Also, z + x + y = 180°
| Angle sum property of a triangle
⇒ 10° + 10° + y = 180°
⇒ y = 160°