bag of rice is eaten (2/5), and there are 30 kilograms left. How many kilograms does this bag of rice originally weigh?
一袋大米，吃了(2/5)，还剩30千克，这袋大米原来有多少千克．
<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>