Asample of dna from a human skin cell contains 32% cytosine bases. approximately what percentage of the bases in this sample will be thymine

18%.
If a cell contains 32% cytosine then it contains the same amount of its base pair, guanine. That means 64% of the cell is cytosine and guanine. The remaining 32% must be adenine and thymine, of which there should be equal amounts. Therefore to fine the amount of thymine divide 32 in half, which gives you 18%.