A 220-liter barrel has a small leak. It lost 10% of its contents before anyone noticed. How many liters are left in the barrel?
The barrel lost 220 * 10 / 100 = 
<gadget id="calculator">220*10/100</gadget>
<output>22</output>
22 liters before anyone noticed.
So, 220 - 22 = 
<gadget id="calculator">220-22</gadget>
<output>198</output>
198 liters are left in the barrel.

<result>198</result>