factory used 360 tons of water in September last year and 210 tons in September this year. How many tons of water is saved on average every day?
某工厂去年9月份用水360吨，今年9月份用水210吨，平均每天节约用水多少吨？
<gadget id="calculator">360 - 210</gadget>
<output>150</output>

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

<result>5</result>