For a pile of coal, (2/5) of the total amount was removed on the first day, and (1/3) of the total amount was removed on the second day, what fraction of this pile of coal is left?
一堆煤，第一天运走了总数的(2/5)，第二天运走了总数的(1/3)，还剩下这堆煤的几分之几？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

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

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