Question

If $l\parallel m$, find the value of '$x$'.

Answer 1

Here $l\parallel m$ and $p$ is transversal
Therefore ${(3x+20)}^o+{(5x-8)}^o={180}^o$ (sum of the interior angles on the same side of a transversal)
$3x+{20}^o+5x-8^o={180}^o$
$8x+{12}^o={180}^o$
$8x={180}^o-{12}^o$
$8x={168}^o$
$x=\frac{{168}^o}{8}={21}^o$