The chemical formula for vitamin A, which contains 20 carbon atoms, 30 hydrogen atoms, and 1 oxygen atom, is:
\[
\boxed{\text{C}_{20}\text{H}_{30}\text{O}}
\]
The chemical formula for aspirin, which contains 9 carbon atoms, 8 hydrogen atoms, and 4 oxygen atoms, is:
\[
\boxed{\text{C}_{9}\text{H}_{8}\text{O}_{4}}
\]