5 kg of peanuts can be squeezed out of 2.1 kg of peanut oil. According to this calculation, how many kilograms of peanuts are needed to squeeze out 31.5 kilograms of peanut oil?
5千克花生可榨出2.1千克花生油．照这样计算，要想榨出31.5千克花生油，需要多少千克花生？
<gadget id="calculator">2.1 / 5</gadget>
<output>0.42</output>

<gadget id="calculator">31.5 / 0.42</gadget>
<output>75</output>

<result>75</result>