Ideal Gas Law — Overview & Calculations

(2016 U.S. National Chemistry Olympiad Local Section Exam #13) A sample of $\text{O}_2$ gas at a given temperature and pressure has a density of $1.30 \text{g L}^{-1}.$ What is the density of gaseous propane $\left(\text{C}_3\text{H}_8\right)$ under the same conditions?