I ate a bag of rice in the first half of the month (2/5) and in the second half of the month (1/4). Have you finished eating this bag of rice? If not finished, how much is left?
一袋大米，上半月吃了(2/5)，下半月吃了(1/4)，这袋大米吃完了没有？如果没有吃完，还剩几分之几？
<gadget id="calculator">13 / 20</gadget>
<output>13/20 = around 0.65</output>

<gadget id="calculator">1 - (13/20)</gadget>
<output>7/20 = around 0.35</output>

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