Question

How many degrees are there in an angle which equals one-fifth of its supplement?

• A. $15{}^o$
• B. ${30}^o$
• C. ${75}^o$
• D. ${150}^o$

Answer 1

The correct option is B ${30}^o$

Let the angle in degrees be $x$. Then, its supplement $=({180}^o-x)$
Given, $x=\frac{1}{5}({180}^o-x)$
$\Rightarrow$ $5x={180}^o-x$ $\Rightarrow$ $6x={180}^o$
$\Rightarrow$ $x={30}^o$