primary school plans to use 200 tons of water for the whole year this year, saving 50 tons of water compared with last year. What percentage of water will be saved this year compared to last year?
某小学今年计划全年用水200吨，比去年节约用水50吨，今年比去年计划节约用水百分之几？
<gadget id="calculator">200 + 50</gadget>
<output>250</output>

<gadget id="calculator">50 / 250</gadget>
<output>1/5 = around 0.2</output>

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