There are four different bases that make the DNA molecule:
Adenine, Cytosine, Guanine, and Thymine.
Due to chemical properties of the bases, there are two pairs of bases that are complementary, Adenine and Thymine and Guanine and Cytosine.
So, if we have 16% of Adenine, there must be the same amount of Thymine, since they only appear in a pair.
16% of Adenine + 16% of Thymine - 32 %
the rest of the abundance of the bases can be calculated by subtracting the 32% out of the 100%: 100-32 = 68
So, Guanine and Cytosine make up 68% of the bases, and a half of that number is the amount each of the bases has in the total amount. 68/2= 34
16% Adenine - 16% Thymine
34% Guanine - 34% Cytosine
