There are 75 tons of flour, 60% of which are sold, how many tons are left
有75吨面粉，卖出了60%，那么还剩下多少吨
<gadget id="calculator">60 / 100</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">1 - (3/5)</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">75 * (2/5)</gadget>
<output>30</output>

<result>30</result>