Let's call the measure of one angle x. Then the measure of its supplementary angle is x + 180.
According to the problem, the measure of one angle is 102° more than the measure of its supplementary angle:
x = x + 180 + 102
-102 = 180
x = 78°
So, one angle measures 78° and its supplementary angle measures 78° + 180 = 258°.