A batch of fruit weighs 50kg, 25kg is sold on the first day, and all (2/5) are sold on the second day, how many kilograms are left.
一批水果重50kg，第一天卖25kg，第二天卖出全部的(2/5)，还剩下多少kg．
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">50 * (2/5)</gadget>
<output>20</output>

<gadget id="calculator">50 - 20 - 25</gadget>
<output>5</output>

<result>5</result>