Determination of the basis angle in a tilted equilateral triangle

Question

I'm trying to solve a geometry problem involving intersecting lines and angles in an equilateral triangle. Could you please explain how to find the measure of the angle marked with a question mark, given that the second marked angle is 71 degrees?

In the sketch, an equilateral triangle is intersected by a pair of parallel lines. Determine the measure of the angle marked with a question mark, given that the second marked angle is 71 degrees.

Here is the sketch:

sketch1

Hope for an answer. Thank you in advance!

Answer 1

Here are the steps:-

1. The 60 $^\circ$ comes from the fact that triangle is equilateral.
2. The 71 $^\circ$ comes from the corresponding angle property of parallel lines.
3. The 109 $^\circ$ comes from linear pair of angles.
4. The 169 $^\circ$ comes from the exterior angle property of triangle.

Hope it helps!