# A sample of C_3H_8 has 6.72 times 10^24 H atoms. How many carbon atoms does the sample contain?

Would this not simply be $\frac{3}{8} \times 6.72 \times {10}^{24}$ $\text{carbon atoms}$?
If we have $6.72 \times {10}^{24}$ hydrogen atoms in the propane sample, surely given the formula of propane, i.e. ${C}_{3} {H}_{8}$, there would be $\frac{3}{8} \times 6.72 \times {10}^{24}$ individual carbon atoms......
The numbers here are pretty irrelevant (meaning that I could choose any number), save that we also know that $\text{Avogadro's Number}$ of $\text{propane molecules}$, $6.022 \times {10}^{23}$ individual molecules of propane, has a mass of $44.1 \cdot g$. Can you tell us the mass of the given quantity of propane in the question?