Last semester, the school canteen actually saved 2/7 more water than the original plan, and actually saved 70 tons of water compared to the original plan. How many tons of water did the school originally plan to use last semester?
上学期学校食堂实际用水比原计划节约了(2/7)，实际比原计划节约用水70吨，上学期学校原计划用水多少吨？
<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">70 / (2/7)</gadget>
<output>245</output>

<result>245</result>