a side of the triangle below has been extended to form an exterior angle of 70°. find the value of x.

Explanation:

Step1: Recall exterior - angle property

The exterior - angle of a triangle is equal to the sum of the two non - adjacent interior angles.

Step2: Set up the equation

We know that the exterior angle is $70^{\circ}$ and the two non - adjacent interior angles are $x^{\circ}$ and $40^{\circ}$. So, $x + 40=70$.

Step3: Solve for $x$

Subtract 40 from both sides of the equation: $x=70 - 40$. $x = 30$

Answer:

$30$