#### Answer

$8625$ dollars; see explanations.

#### Work Step by Step

Step 1. Checking the value $x=50,000$, it falls on the interval of $34,500\lt x\leq 83,600$. Thus we should use the third equation.
Step 2. We have $T(50,000)=4750.00 + 0.25(50,000 - 34,500)=8625$ dollars.
Step 3. This means that for a single taxpayer of income $50,000$ dollars, the tax would be $8625$ dollars.