Answer
$0.764atm$, $77.5KPa$
Work Step by Step
First, we find the atmospheric pressure in $atm$
As $760mm\space Hg=1atm$
$\implies 1mm\space Hg=\frac{1}{760}atm$
$\implies 581mm\space Hg=581\times \frac{1}{760}=0.764atm$
Now, we find atmospheric pressure in $KPa$
As As $760mm\space Hg=101.325KPa$
$\implies 1mm\space Hg=\frac{101.325}{760}KPa$
$\implies 581mm\space Hg=581\times \frac{101.325}{760}=77.5KPa$
