A bag of potatoes is eaten (3/5), and 30 kilograms are eaten, how many kilograms are left in this bag of potatoes.
一袋土豆，吃了(3/5)，吃了30千克，这袋土豆还剩下多少千克．
<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">30 / (3/5)</gadget>
<output>50</output>

<gadget id="calculator">50 - 30</gadget>
<output>20</output>

<result>20</result>