Answer:
180° (in place of blank)
Step-by-step explanation:
<u><em>GIVEN</em></u><em> :-</em>
<u><em>PROCEDURE</em></u><em> :-</em>
∠C & ∠D are linear pair. (∵ They lie on same line)
⇒ ∠C + ∠D = 180°
⇒ ∠C = 180° - 127°
In a triangle , sum of its all interior angles equals to 180° (which is also known as "Angle Sum Property). So,
∠A + ∠B + ∠C = 180°
⇒ 75° + ∠B + (180° - 127°) = 180°
⇒ ∠B = 180° - 75° - (<u>180°</u> - 127°)