Question

what is the value of x? 55° 105° a. 50° b. 160° c. 55° d. 20°

Explanation:

Step1: Use exterior - angle property

The exterior - angle of a triangle is equal to the sum of the two non - adjacent interior angles. Let the exterior angle be $105^{\circ}$, and the two non - adjacent interior angles be $55^{\circ}$ and $x$. So, $105^{\circ}=55^{\circ}+x$.

Step2: Solve for $x$

Subtract $55^{\circ}$ from both sides of the equation: $x = 105^{\circ}-55^{\circ}$.

Answer:

D. $20^{\circ}$