Answer
$\color{blue}{\text{(a)}79.8\text{ ppb}}$
$\color{blue}{\text{(b)}87.7\text{ ppb}}$
Work Step by Step
To find the amount $y$ of ozone after filtration
$140-0.43(140)=y$
$140-60.2=y$
$\color{blue}{\text{(a)}79.8\text{ ppb}}$
To find the amount, $x$, of initial ozone the filter can reduce below $50$ ppm:
$x-0.43x<50$
$0.57x<50$
$x<87.7$
$\color{blue}{\text{(b)}87.7\text{ ppb}}$
