Answer
$75\%$.
Work Step by Step
The given function is
$\Rightarrow f(x)=\frac{250x}{100-x}$.... (1)
Plug $f(x)=750$ in (1) and solve for $x$.
$\Rightarrow 750=\frac{250x}{100-x}$
Multiply both sides by $(100-x)$.
$\Rightarrow 750\cdot (100-x)=\frac{250x}{100-x}\cdot (100-x)$
Use the distributive property on the left and cancel common factors on the right.
$\Rightarrow 75000-750x=250x$
Add $750x$ to both sides.
$\Rightarrow 75000-750x+375x=250x+750x$
Simplify.
$\Rightarrow 75000=1000x$
Divide both sides by $1000$.
$\Rightarrow \frac{75000}{1000}=\frac{1000x}{1000}$
Simplify.
$\Rightarrow 75=x$
Hence, $75\%$ of the pollutants can be removed.
