Answer:
50
Explanation:
You want the value of x in the attached diagram.
Alternate interior angles
If the upper interior segment is extended to the lower horizontal line, the angle it makes inside the triangle is an "alternate interior angle" with respect to the one marked 20°. Hence it is congruent.
Remote interior angles
With respect to angle x°, now the angles 20° (just made, above) and 30° are "remote interior angles." Hence, their sum is the value of the exterior angle x°:
x° = 20° +30°
x° = 50°
x = 50
The value of x is 50.