Ideal gas equation is given as:
$PV = nRT$
$P =$ Pressure of gas,
$V =$ volume of gas
$n =$ moles of gas,
$R =$ gas constant
$T=$ temperature
$\Rightarrow P V=\frac{w}{M} R T$
$ w =$ mass of gas
$M =$ Molecular mass of gas
$P=\left(\frac{w}{V}\right) \frac{R T}{M} $
$\Rightarrow P=\rho \frac{R T}{M}$
$\left(A s \rho=\frac{w}{V}\right)$
$\Rightarrow P \mu \rho$