SIPG finished shipping a batch of steel products in three days, shipped (1/5) of the total on the first day, (1/4) of the total on the second day, and what fraction of the total was shipped on the third day?
上港码头三天运完一批钢材，第一天运了总数的(1/5)，第二天运了总数的(1/4)，第三天运了总数的几分之几？
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (1/5) - (1/4)</gadget>
<output>11/20 = around 0.55</output>

<result>11/20 = around 0.55</result>