### Video Transcript

Work out the value of 𝑥 in the
figure.

𝑥 is an angle that’s measured in
degrees, and there’s another angle that measures 131 degrees. We have a set of parallel lines
that are cut by a transversal. This means the angle that’s 131
degrees is going to be equal to another angle that is supplementary to 𝑥.

We know the angles measuring 131
degrees are equal because they are alternate exterior angles; they’re on alternate
sides of the transversal and on the exterior of the parallel lines.

So these two angles should add to
180 degrees because they form a linear pair; they create a line, which is 180
degrees; they are supplementary. Therefore, we can say 131 plus 𝑥
equals 180 because these two angles added together will combine to equal 180
degrees.

So to solve for 𝑥, we need to
subtract both sides by 131. And we get that 𝑥 is equal to
49. Therefore, the value of 𝑥 in our
figure is 49 degrees.