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%.
