Respuesta :
Answer: 100
Step-by-step explanation:m∠DAB = m∠CDA = 80°
The sum of the angles in a quadrilateral is 360°. This gives the equation:
m∠DAB + m∠ABC + m∠BCD + m∠ = 360°
→ 80° + m∠ABC + m∠BCD + 80° = 360°
→ m∠ABC + m∠BCD = 360° - 80° - 80° = 200°
&rarr 2 x m∠BCD = 200°
→m∠BCD = 100°
