Xingxing Primary School used 84 tons of water in June, saving 20% compared to May. How many tons of water was saved in June compared to May?
星星小学六月份用水84吨，比五月份节约了20%．六月份比五月份节约用水多少吨？
<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">84 / (4/5)</gadget>
<output>105</output>

<gadget id="calculator">105 - 84</gadget>
<output>21</output>

<result>21</result>