The school used 36 tons of water in October, saving (1/7) compared to September. How many tons of water was used in September?
学校十月份用水36吨，比九月份节约了(1/7)，九月份用水多少吨？
<gadget id="calculator">1 / 7</gadget>
<output>1/7 = around 0.142857</output>

<gadget id="calculator">1 - (1/7)</gadget>
<output>6/7 = around 0.857143</output>

<gadget id="calculator">36 / (6/7)</gadget>
<output>42</output>

<result>42</result>