Question

An angle is ${20}^{\circ }$ less than thrice its supplement. Find the angle.

• A. ${150}^{\circ }$
• B. ${130}^{\circ }$
• C. ${90}^{\circ }$
• D. ${62.5}^{\circ }$

Answer 1

The correct option is B

${130}^{\circ }$

Let the angle be $x^{\circ }$.

Then, its supplement
$=(180-x{)}^{\circ }$

$\Rightarrow 3(180-x)-x=20$

$\Rightarrow 540-3x-x=20$

$\Rightarrow 4x=520$

$\Rightarrow x={130}^{\circ }$