A factory used 5,400 tons of water in November, and saved 20% of water in December compared with November. How many tons of water was used in December?
某工厂十一月份用水5400吨，十二月份比十一月份节约用水20%，十二月份用水多少吨？
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">5_400 * (4/5)</gadget>
<output>4_320</output>

<result>4_320</result>