Answer: x = 100
Explanation:
In the Figure, both the Angles form a Linear pair which means they sum up to 180 degrees.
Therefore,
57 + x + 23 = 180
57 + 23 + x = 180
80 + x = 180
x = 180 - 80
=> x = 100
Therefore, x = 100
Also finding the missing Angle :-
= x + 23
= 100 + 23
=> 123
The Angle is 123 degrees.