There are some fruits in the fruit shop. They sold (1/4) on the first day and (2/5) on the second day. How many are left unsold?
水果店有一些水果，第一天卖出了(1/4)，第二天卖出了(2/5)，还剩下多少没有卖？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (1/4) - (2/5)</gadget>
<output>7/20 = around 0.35</output>

<result>7/20 = around 0.35</result>