First off, the Triangle Sum Theorem states that every triangle must equal 180 degrees. To find the value of x, we need to first find the value of the missing angle, and then subtract the two known values from 180.
Since the images are the same, just rotated, the image to the left gives us our missing angle value for the image on the right, which is 72. 72 + 52 = 124. We can now subtract 124 from 180 to get the value of x. 180 - 124 = 56
56 is your answer