25% of a barrel of oil is used, and there are 12 kilograms left. How many kilograms of oil is in this barrel?
一桶油用去25%，还剩12千克，这桶油多少千克？
<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (1/4)</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">12 / (3/4)</gadget>
<output>16</output>

<result>16</result>