Question

X = [?]°
Dr.
X Х
As
140°
B
C

Answer 1

40°

Explanation:

x+140=180°(angle on a straight line)

x=180-140

x=40°

Answer 2

∠DBA and ∠DBC are making linear pair.

Linear pair of angles are formed when two lines intersect each other at a single point.

• The sum of angles of a linear pair is always equal to 180°

`\rm \large\longrightarrow \: \: x \: + \: 140 \degree \: = \: 180 \degree`

`\rm \large\longrightarrow \: \: x \: = \: 180 \degree \: - \: 140 \degree \:`

`\rm \large\longrightarrow \: \: x \: = \: 40 \degree`