Question

a side of the triangle below has been extended to form an exterior angle of 144°. find the value of x.

Explanation:

Step1: Use linear pair property

The exterior angle and $a$ form a linear pair, so they add to $180^\circ$.
$144^\circ + a = 180^\circ$

Step2: Solve for $a$

Subtract $144^\circ$ from both sides.
$a = 180^\circ - 144^\circ$

Answer:

$36^\circ$