Question

If $\angle ABC=x+y$ and $\angle PQR=x-y$ are supplementary angles, the value of $x$ is:

• A. ${30}^o$
• B. ${60}^o$
• C. ${90}^o$
• D. ${120}^o$

Answer 1

The correct option is C ${90}^o$

Since $\angle ABC=x+y$ and $\angle PQR=x-y$ are supplementary angles, we have

$(x+y)+(x-y)={180}^o$
$\Rightarrow 2x={180}^o\Rightarrow x={90}^o$