A country used to have a tax rate of 20%.  They raised it to 30%.  In that same time frame, John went from making 1,000,000 a year to 1,500,000 a year.  How much more does he pay in taxes now compared to then?
At 20% he paid .2*1000000=$
<gadget id="calculator">.2*1000000</gadget>
<output>200_000</output>
200,000.
Now he pays 1500000*.3=$
<gadget id="calculator">1500000*.3</gadget>
<output>450_000</output>
450,000.
So he pays an extra 450000-200000=$
<gadget id="calculator">450000-200000</gadget>
<output>250_000</output>
250000.

<result>250_000</result>