The school used 120 tons of water in May, saving 30 tons compared with April. How much was the saving?
学校5月份用水120吨，比4月份节约了30吨，节约了百分之几？
<gadget id="calculator">120 + 30</gadget>
<output>150</output>

<gadget id="calculator">30 / 150</gadget>
<output>1/5 = around 0.2</output>

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