Cytosine makes up 30% of the nucleotides in a sample of DNA from an organism. What percent of the nucleotides in this sample will be adenine?

20%

Explanation:

The four different bases pair together in a way known as complementary pairing. Adenine always pairs with thymine, and cytosine always pairs with guanine.

if adenine makes

The guanine percent is 30. This is because the other 30% of the 60% is cytosine. Getting back to adenine, it always partners up with thymine as i mentioned before, So it would be 20% thymine and 20% adenine, add those portions to the 60% of the other two, mentioned above and you have 100%.

where is the diagram?

if you insert the diagram ill be able to you