A factory now uses 80 tons of water per day, which is 20 tons less than before. How much has been saved?
某工厂现在每天用水80吨，比原来节约20吨，节约了多少．
<gadget id="calculator">80 + 20</gadget>
<output>100</output>

<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<result>1/5 = around 0.2</result>