Last month, Weimin Canteen actually used 3.4 tons of coal, which was 20% less than planned. How many tons were saved?
为民食堂上月实际用煤3.4吨，比计划节约20%，节约了多少吨．
<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">3.4 / (4/5)</gadget>
<output>4.25</output>

<gadget id="calculator">4.25 * (1/5)</gadget>
<output>0.85</output>

<result>0.85</result>