A bag of potatoes, after eating (2/5), there are 30 kilograms left, how many kilograms are there in this bag of potatoes?
一袋土豆，吃了它的(2/5)，还剩30千克，这袋土豆原有多少千克．
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

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

<result>50</result>