Answer:

Explanation:
The Triangle external angle theorem states that :An exterior angle of a triangle is equal to the sum of the opposite interior angles. For more on this see
see the attached figure with letter to better understand the problem
step 1
Find the measure of the interior angle at B
we know that
----> by supplementary angles (form a linear pair)

step 2
Find the value of x
Applying the triangle external angle theorem

solve for x



simplify
