A factory used 320 tons of water in May, but actually only used 280 tons. What percentage was saved?
某工厂5月份的用水指标是320吨，实际只用了280吨，节约了百分之几？
<gadget id="calculator">320 - 280</gadget>
<output>40</output>

<gadget id="calculator">40 / 320</gadget>
<output>1/8 = around 0.125</output>

<result>1/8 = around 0.125</result>