John has to pay taxes.  He earned $100,000 for the year.  He has $30,000 in deductions.  The first $20,000 of taxable income is taxed at 10%.  The rest is taxed at 20%.  How much does he pay in taxes?
His taxable income is 100,000-30,000=$
<gadget id="calculator">100000-30000</gadget>
<output>70_000</output>
70,000.
So he pays 20,000*.1=$
<gadget id="calculator">20000*.1</gadget>
<output>2_000</output>
2000 tax at the lower rate.
He has to pay 70,000-20,000=$
<gadget id="calculator">70000-20000</gadget>
<output>50_000</output>
50,000 at the higher rate.
The taxes for that is 50,000*.2=$
<gadget id="calculator">50000*.2</gadget>
<output>10_000</output>
10,000.
So his total tax bill is 10,000+2,000=$
<gadget id="calculator">10000+2000</gadget>
<output>12_000</output>
12,000.

<result>12_000</result>