What is the format of this proof? Given: ∠ABC is a right angle, ∠DBC is a straight angle Prove: ∠ABD is a right angle

It's a two column proof.

Given : ∠ABC is a right angle, ∠D BC is a straight angle.

To prove : ∠AB D is a right angle.

Proof: ∠ ABC = 90°[ Given]

∠ D BC = 180° [ D BC is a straight line]

now, ∠ AB D and ∠ AB C are adjacent angles forming linear pair.

∠ AB D + ∠ AB C = 180° [By linear pair axiom]

⇒∠ AB D + 90 = 180°

⇒∠ AB D=180°-90°

⇒∠ AB D=90°

∠AB D is a right angle

Hence proved.