6 times of a number minus 2 times of 3.5, the difference is 71, find this number.
一个数的6倍减去3.5的2倍，差是71，求这个数．
<gadget id="calculator">3.5 * 2</gadget>
<output>7</output>

<gadget id="calculator">71 + 7</gadget>
<output>78</output>

<gadget id="calculator">78 / 6</gadget>
<output>13</output>

<result>13</result>