A bag of flour, if (2/5) of it is eaten and there are 30 kilograms left, if (3/5) of it is eaten, how many kilograms will it be?
一袋面粉，吃掉它的(2/5)还剩30千克，若吃掉它的(3/5)是多少千克．
<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>

<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

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

<result>30</result>