After adopting water-saving measures, Uncle Zhang’s family used 10 tons of water in October, saving (1/5) compared to September. How many tons of water did Uncle Zhang’s family use in September?
采取节水措施后，张大爷家十月份用水10吨，比九月份节约(1/5)，张大爷家九月份用水多少吨？
<gadget id="calculator">1 / 5</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">10 / (4/5)</gadget>
<output>25/2 = around 12.5</output>

<result>25/2 = around 12.5</result>