Xiaohong’s family used 36 tons of water this year, which is 4 tons less than last year. What percentage is the saving compared to last year?
小红家今年用水36吨，比去年节约了4吨，比去年节约了百分之几？
<gadget id="calculator">36 + 4</gadget>
<output>40</output>

<gadget id="calculator">4 / 40</gadget>
<output>1/10 = around 0.1</output>

<result>1/10 = around 0.1</result>