A new pile of coal was added to the coal yard, and 2/5 of the total amount was sold in November, and 9 tons were sold in December, and a total of 17 tons were sold in two months. How many tons of this pile of coal are there?
煤场新进了一堆煤，11月份卖了总量的(2/5)，12月份卖了9吨，两个月一共卖了17吨，这堆煤共有多少吨？
<gadget id="calculator">17 - 9</gadget>
<output>8</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">8 / (2/5)</gadget>
<output>20</output>

<result>20</result>