Answer:
C. [tex]x=180^o-(31^o+40^o)[/tex]
Step-by-step explanation:
We have been given a figure of angles formed on a straight line.
Since we know that the angles on a straight line add up-to 180 degrees. Upon using this property we can set an equation as:
[tex]31^o+x^o+40^o=180^o[/tex]
Let us subtract 40 and 31 degrees from both sides of our equation to solve to x.
[tex]31^o-31^o+x^o+40^o-40^o=180^o-31^o-40^o[/tex]
[tex]x=180^o-31^o-40^o[/tex]
Upon factoring negative sign from right side of our equation we will get,
[tex]x=180^o-(31^o+40^o)[/tex]
Therefore, the equation [tex]x=180^o-(31^o+40^o)[/tex] can be used to find the value of x and option C is the correct choice.