Question

In figure, If $l_1\parallel l_2$, calculate the value of $x$.

• A. ${15}^o$
• B. ${25}^o$
• C. ${30}^o$
• D. ${35}^o$
• E. $40$

Answer 1

The correct option is D ${35}^o$

Since the two lines are parallel, the suplementary angle of angle $(4x-30{)}^o$ is equal to sum of two $x$ angles.(Corresponding angles of parallel lines)
${180}^o-(4x-30)=x+x$
$4x-{30}^o+2x={180}^o$
$\Rightarrow 6x={210}^o$

$\Rightarrow x={35}^o$