Answer:
There should be 10% thymine
Explanation:
DNA bases come in specific pairs. Guanine pairs up with cytosine and adenine pairs up with Thymine.
According to the problem the DNA sample was 40% cytosine and 40% guanine, so this is correct, there are equal amounts of cytosine and guanine. Now Thymine needs to have equal amounts as adenine, but adenine only has 10%.
If we match up the amount of adenine to thymine, we would have 15% adenine and 15% thymine, but that would excede 100%. So you need to match the thymine to adenine.
10% adenine + 10 % thymine + 40% cytosine + 40% guanine = 100%
