A pile of coal weighs 220 tons. (1/5) is used on the first day and (1/4) is used on the second day. How many tons are left?
一堆煤重220吨，第一天用去(1/5)，第二天用去(1/4)，还剩多少吨？
<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>

<gadget id="calculator">220 * (11/20)</gadget>
<output>121</output>

<result>121</result>