The school uses 150 tons of water this year, which is 50 tons less than last year. What percentage has been saved?
学校今年用水150吨，比去年节约了50吨，节约了百分之几？
<gadget id="calculator">150 + 50</gadget>
<output>200</output>

<gadget id="calculator">50 / 200</gadget>
<output>1/4 = around 0.25</output>

<result>1/4 = around 0.25</result>