Question

solve for x in the following figure. answer:

Explanation:

Step1: Use exterior - angle property

The exterior - angle of a triangle is equal to the sum of the two non - adjacent interior angles. So, $x + 20^{\circ}=60^{\circ}+40^{\circ}$.

Step2: Simplify the right - hand side

$60^{\circ}+40^{\circ}=100^{\circ}$, so the equation becomes $x + 20^{\circ}=100^{\circ}$.

Step3: Solve for x

Subtract $20^{\circ}$ from both sides: $x=100^{\circ}-20^{\circ}$.

Answer:

$80^{\circ}$