Xiaofei's family used 20 tons of water in April and 18 tons in May. What percentage did Xiao Feijia save water in May compared to April?
小飞家四月份用水20吨，五月份用水18吨．小飞家五月份用水比四月份节约百分之几？
<gadget id="calculator">20 - 18</gadget>
<output>2</output>

<gadget id="calculator">2 / 20</gadget>
<output>1/10 = around 0.1</output>

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