Question

If the line $l_1$ is parallel to line $l_2$ in the given figure, what is the value of $y$?

• A. ${141}^o$
• B. ${142}^o$
• C. ${143}^o$
• D. None of the above

Answer 1

The correct option is A ${141}^o$

$l_1\parallel l_2$

${115}^{\circ }+2x+3x={180}^{\circ }$ (Co-interior angles)
$5x={180}^{\circ }-{115}^{\circ }={65}^{\circ }$
$x={13}^{\circ }$
Also, $y+3x={180}^{\circ }$ (co-interior angles)
$y+{39}^{\circ }={180}^{\circ }$

$y={180}^{\circ }-{39}^{\circ }={141}^{\circ }$