Question

Find the measure of an angle which is one-fifth of its supplement.

• A. ${15}^{\circ }$
• B. ${30}^{\circ }$
• C. ${45}^{\circ }$
• D. ${60}^{\circ }$

Answer 1

Answer: (B)

${30}^{\circ }$

Let the desired angle be $x$. According to the question,
$\Rightarrow x=\frac{1}{5}(180-x)$

$\Rightarrow 6x=180$

$\Rightarrow x={30}^{\circ }$