Qingyun Primary School used 440 cubic meters of water in October, saving 20% compared to September. How many cubic meters of water was used in September? (solution by equation)
青云小学十月份用水440立方米，比九月份节约20%，九月份用水多少立方米？(用方程解)
<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">440 / (4/5)</gadget>
<output>550</output>

<result>550</result>