The fertilizer plant used 40 tons of coal in June, which was 1/5 less than in May. How many tons of coal was used in May?
化肥厂六月份用煤40吨，比五月份节约了(1/5)，五月份用煤多少吨？
<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">40 / (4/5)</gadget>
<output>50</output>

<result>50</result>