A pile of coal (7/9) tons, used up (3/11) on the first day. (3/11) tons are used up the next day, how many tons are left?
一堆煤(7/9)吨，第一天用去(3/11)．第二天用去(3/11)吨，还剩多少吨？
<gadget id="calculator">7 / 9</gadget>
<output>7/9 = around 0.777778</output>

<gadget id="calculator">3 / 11</gadget>
<output>3/11 = around 0.272727</output>

<gadget id="calculator">1 - (3/11)</gadget>
<output>8/11 = around 0.727273</output>

<gadget id="calculator">(7/9) * (8/11)</gadget>
<output>56/99 = around 0.565657</output>

<gadget id="calculator">(56/99) - (3/11)</gadget>
<output>29/99 = around 0.292929</output>

<result>29/99 = around 0.292929</result>