One pushes the coal, and after using up (2/3) there are still 9 tons left. How many tons are there in this pile of coal?
一推煤，用去它的(2/3)还剩9吨，这堆煤有多少吨．
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">1 - (2/3)</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">9 / (1/3)</gadget>
<output>27</output>

<result>27</result>