a) The RNA molecule is likely to be single-stranded. If the molecule was double-stranded, we would expect nearly equal percentages of adenine and uracil, as well as equal percentages of guanine and cytosine. In this RNA molecule, the percentages of these potential base pairs are not equal, so the molecule is single-stranded.
b) Because the DNA template strand is complementary to the RNA molecule, we would expect equal percentages for bases in the DNA complementary to the RNA bases. Therefore, in the DNA we would expect A = 42%, T = 23%, C = 14%, and G = 21%.