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It is given that ABCD is parallelogram and ∠DAB = 80°​ and ∠DBC = 60°
We need to find measure of ∠CDB and ∠ADB
In ABCD, AD ||​ BC, BD as transversal,
∠DBC = ∠ ADB = 60° …Alternate interior angles ...(i)
As ∠DAB and ∠ADC are adjacent angles,

∠DAB ​+ ∠ADC​ = 180°
∴ ∠ADC = 180°° − ∠DAB
​∠ADC​ = 180° − 80° = 100°
Also,

∠ADC​ = ∠ADB + ∠C​​DB
∴​ ∠ADC​ =​ 100°
∠ADB + ∠C​​DB = 100° ...(ii)
From (i) and (ii), we get:
60° + ∠C​​DB = 100°
⇒ ∠C​​DB = 100° − 60° = 40°
Hence, ∠CDB​ =​ 40° and ∠ADB​ = 60°​