Answer
Tax owed from a single taxpayer is $\$2575$.
Work Step by Step
To calculate tax owed from taxable income of $20000$, put $x=20000$ in the piecewise function $T\left( x \right)$.
For the range of, $\text{8500}x\le 34500$
$\begin{align}
& T\left( x \right)=850+0.15\left( x-8500 \right)\text{ } \\
& T\left( 20000 \right)=850+0.15\left( 20000-8500 \right) \\
& =2575
\end{align}$
