After 40% of a bag of flour has been eaten, there are 30 kilograms left. How many kilograms are there in this bag of flour?
一袋面粉吃掉40%后，还剩下30千克，这袋面粉共有多少千克．
<gadget id="calculator">40 / 100</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>