A store decides to shut down and sell all of its inventory.  They have 2000 different items which would normally retail for $50.  They are offering an 80% discount and manage to sell 90% of the items.  They owed $15000 to their creditors.  How much money do they have left after the sale?
They sold 2000*.9=
<gadget id="calculator">2000*.9</gadget>
<output>1_800</output>
1800 items.
They offered a 50*.8=$
<gadget id="calculator">50*.8</gadget>
<output>40</output>
40 discount.
That means that each item sold for 50-40=$
<gadget id="calculator">50-40</gadget>
<output>10</output>
10.
So they made 1800*10=$
<gadget id="calculator">1800*10</gadget>
<output>18_000</output>
18,000.
So they had 18,000-15,000=$
<gadget id="calculator">18000-15000</gadget>
<output>3_000</output>
3,000 leftover.

<result>3_000</result>