There are 10 judgment questions in an intelligence test, 3 points are awarded for each correct answer, and 1 point is deducted for each incorrect answer. Xiaohong finished answering 10 questions and only scored 18 points. How many questions did she get wrong?
一次智力测验有10道判断题，每答对一道得3分，每答错一道不得分还扣1分．小红答完了10道题，只得了18分，她答错了多少道题．
<gadget id="calculator">10 * 3</gadget>
<output>30</output>

<gadget id="calculator">30 - 18</gadget>
<output>12</output>

<gadget id="calculator">3 + 1</gadget>
<output>4</output>

<gadget id="calculator">12 / 4</gadget>
<output>3</output>

<result>3</result>