a) 13 degrees because it would be 90-77
If two angles are complementary, then the two angles add up to 90 degrees.
If angle A is 77, then the complement would be 90-77 or 13 degrees.
b) The complement of the complement of the angle is the angle itself.
Say the angle A is 30 degrees. It's complement is 90-30 or 60 degrees.
The complement of the 60 degrees is 30 degrees.
So the complement of the complement of the angle would be the angle itself.
Hope this helps :)