The farm harvested 270 tons of grain this year, an increase (2/7) compared to last year. How many tons of grain were harvested last year?
农场今年收获粮食270吨，比去年增产了(2/7)，去年收获粮食多少吨？
<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">1 + (2/7)</gadget>
<output>9/7 = around 1.285714</output>

<gadget id="calculator">270 / (9/7)</gadget>
<output>210</output>

<result>210</result>