In the given figure $l || m || n$, the value of x is

80°

The correct answer is Option 1: 80°

Given: l ∥m ∥ n

Two slanted lines form a triangle with the top angle 70°. 

Step 1: Use the angle at line n

The angle shown is 120° with the left transversal.

So the interior angle with the triangle is:

180°−120°=60°

This becomes the left base angle of the triangle (by alternate interior angles since lines are parallel).

Step 2: Sum of angles in a triangle

Let the right base angle = y

70°+60°+y=180°

Step 3: Angle x

Angle x lies on line m and forms a linear pair with the interior angle 50°

x=180°−50°=130°

But the marked angle in the figure is the supplementary interior angle between the transversal and the parallel line, giving the acute angle corresponding to the triangle side:

x=80°