Question

In the figure, if AB || CD, then value of x is

Answer 1

In the figure, AB||CD, and l is transversal
$\angle 1=x$ (Vertically opposite angles)
and ${120}^0+x+\angle 1={180}^0$
(Co-interior angles)

$\Rightarrow {120}^0+x+x={180}^0$
$\Rightarrow 2x={180}^0-{120}^0={60}^0$
$\therefore x=\frac{{60}^0}{2}={30}^0$