There are 20 questions in a math competition. It is stipulated that one correct answer will get 2 points, one point will be deducted for wrong answer, and 0 point will be deducted for no answer. Zhao Min got 23 points. It is known that she has an even number of unanswered questions. How many mistakes did he answer? question?
一次数学竞赛共20道题，规定答对一题得2分，答错倒扣1分，不答0分，赵敏得了23分，已知她未答题目数是偶数，他答错了几道题？
<gadget id="calculator">2 * 4</gadget>
<output>8</output>

<gadget id="calculator">17 - 8</gadget>
<output>9</output>

<gadget id="calculator">9 / 3</gadget>
<output>3</output>

<result>3</result>