So You got two parallel lines and a transversal, the transversal forms two angles: (2x+20) and 3x.
If you take close attention... you’ll see that 2x+20 is on the left side of the transversal and 3x is in the right side of the transversal.
That said, we now now that it is Alternate interior angles ( it is interior because these two angles are inside the two parallel lines. Think of it as the angles are the meat of the hamburger and the bread is the parallel lines.
So when they are alternate interior angles, you set them equal to each other because they are equal! They’re the same amount of degrees!
So it goes like...
2x+20=3x
And then you solve for x
So...
20=x when you subtract 2x from both sides.
And that’s it because they’re only asking for the value of x.
Now to prove that they’re equal, you just plug the x value in, like this:
2x+20=3x
2(20)+20=3(20)
40+20=60
60=60
So we just verified it is true that the x value is 20:)
