Fa dna sample were composed of 10% thymine, what would be the percentage of guanine?

There would be 40% of guanine
because 10% thymine means 10% percent of adenine which leaves 80% left for guanine and cytosine which has to be even so 40% would be your answer.

Some of her  assignments would be creation of drugs. she is a medical chemist after all so she'd need to have the necessary knowledge to make medicine which can later be sold in a pharmacy