Question

Find the angle which measure twice of its supplement.

• A. $100$
• B. $110$
• C. $120$
• D. $130$

Answer 1

The correct option is C $120$

Let the required angle be $x$, then its supplement $=(180-x)$ and $x=2(180-x)$

So, $(180-x)+2(180-x)=180$

$\Rightarrow 180-x+360-2x=180$

$\Rightarrow -3x+360=0$

$\Rightarrow -3x=-360$

$\Rightarrow 3x=360$

$\Rightarrow x={120}^o$