There is a pile of coal, 120 tons are used, and the rest is 9 tons less than 5 times the amount used. How many tons is this pile of coal originally?
有一堆煤，用去120吨，剩下的比用去的5倍少9吨，这堆煤原有多少吨？
<gadget id="calculator">120 * 5</gadget>
<output>600</output>

<gadget id="calculator">600 - 9</gadget>
<output>591</output>

<gadget id="calculator">591 + 120</gadget>
<output>711</output>

<result>711</result>