Answer: 28%
Step-by-step explanation:
Use Chargaff's rules which states that 100% is total of all 4 bases and Adenine and Thymine need to have 1:1 ratio and Cytosine and Guanine need to have 1:1 ratio
21% Adenine and 21% Thymine
21% + 21% = 42 100 - 42 = 56 56 / 2 = 28
28% Cytosine and 28% Guanine