Answer:
It would be the transitive property! If you look up "If a = b, and b = c, then a = c" you'd see the transitive property. I hope this helps!
The answer to your question is A.
Given:
The angles are:
Example 
1. 
2. 
3. 
4. 
5. 
To find:
The complimentary angle of the given angles.
Solution:
If two angles are complimentary, then their sum is 90 degrees.
Example: Let x be the complimentary angle of
, then



Similarly,
1. The complimentary angle of
is:

2. The complimentary angle of
is:

3. The complimentary angle of
is:

4. The complimentary angle of
is:

5. The complimentary angle of
is:

Therefore, the complimentary angles of
are
respectively.
You only need a common denominator for adding and subtracting! <span />