The statement is always true because the sum of the two angles must be 180 degrees to be supplementary. If the first angle is an acute angle, then it has a measure of less than 90 degrees. To sum 180 degrees, the second angle would need to be more than 90 degrees, making it an obtuse angle.
I'm not entirely sure what you're looking for, but here are your options. If you need a perfect square, I'd go for the 12 and 12, but I hope this helps?