A sample of gas occupies a volume of   $320c{m}^3$ at STP. Calculate its volume at  ${66}^{0}C$ and 0.825 atm pressure.

Here, 
$\begin{array}{l}{P}_1=1.00atm,P_2=0.825atm\\ V_1=320c{m}^3,V_2=?\\ T_1=273K,\\ T_2={66}^{0}C=(66+273)K=339K\end{array}$
According to the gas equation, 
$\begin{array}{l}\frac{P_1{V}_1}{T_1}=\frac{P_2{V}_2}{T_2}\\ V_2=\frac{P_1{V}_1{T}_2}{T_1{P}_2}=\frac{1\times 320\times 339}{273\times 0.825}=482c{m}^3\end{array}$