There is a pile of chess pieces in which the number of black pieces is 6 times the number of white pieces. It is known that the total number of pieces in this pile is between 80 and 90. So, what is the number of sunspots among them?
有一堆棋子，其中黑子的个数是白子个数的6倍，已知这堆棋子的总数在80与90之间．那么，其中黑子的个数是多少．
<gadget id="calculator">6 + 1</gadget>
<output>7</output>

<gadget id="calculator">84 / 7</gadget>
<output>12</output>

<gadget id="calculator">12 * 6</gadget>
<output>72</output>

<result>72</result>