Describe your reasoning. As guanine and cytosine are complementary, another 15% of the nucleotides must have cytosine. The remaining 70% of the nucleotides (100%-30%) must have adenine and thymine in equal proportions (35% each), as they are complementary to each other.f 15% of the nucleotides in a DNA molecule contain guanine, what percentage of the nucleotides having each of the other three bases?