For a batch of chemical fertilizers, (1/3) is shipped away on the first day, and (2/5) is shipped away on the second day, and the remaining amount of this batch of fertilizers has not been shipped.
一批化肥，第一天运走它的(1/3)，第二天运走它的(2/5)，还剩这批化肥的多少没有运．
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

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

<gadget id="calculator">1 - (1/3) - (2/5)</gadget>
<output>4/15 = around 0.266667</output>

<result>4/15 = around 0.266667</result>