There are 10 questions in the math contest, 8 points for one correct answer, 5 points deducted for wrong answer (or not done), Xiaojun gets 41 points, how many questions did he get wrong (or not done)
数学竞赛共有10题，做对一道的8分，做错一道(或不做)倒扣5分，小军得41分，他做错了(或不做)多少题
<gadget id="calculator">8 * 10</gadget>
<output>80</output>

<gadget id="calculator">80 - 41</gadget>
<output>39</output>

<gadget id="calculator">8 + 5</gadget>
<output>13</output>

<gadget id="calculator">39 / 13</gadget>
<output>3</output>

<result>3</result>