We can see this because Angle 2x and Angle 72 are verticle angles. Based on this information we know that verticle angles are congruent to each other, meaning the are the same. So that leaves us with an equation to figure out x.
<u><em>solution is attached in word form due to error in mathematical equation. furthermore i also attach Screenshot of solution in word due to different version of MS Office please find the attachment</em></u>