Hey there!
If two angles are supplementary, that means that the measures of the two angles have a sum of 180.
If the two angles were of equal measure, they would both be 90 degrees.
The easiest way to get this would be to subtract 12 degrees from one 90 degree angle and add them to the other 90 degree angle so one angle has 24 more degrees then the other.
90 - 12 = 78
90 + 12 = 102
Let's check to make sure this works.
102 + 78 = 180 That checks out.
102 - 24 = 78 That also works.
So, the measures of the angles are 102 and 78.
Hope this helps!