A certain oil mill can extract 420 kg of oil with 1200 kg of rapeseed. According to this calculation, how many tons of rapeseed are needed to squeeze 1 ton of oil.
某榨油厂用1200千克油菜籽能榨420千克的油，照这样计算，要榨1吨油需要多少吨油菜籽．
<gadget id="calculator">420 / 1_200</gadget>
<output>7/20 = around 0.35</output>

<gadget id="calculator">1 / (7/20)</gadget>
<output>20/7 = around 2.857143</output>

<result>20/7 = around 2.857143</result>