There are 10 questions in an intelligence test, 3 points are awarded for each correct answer, and 2 points are deducted for each incorrect answer. Xiaohong finished 10 questions and got 20 points in total. May I ask how many questions Xiaohong got wrong?
一次智力测试共有10道题，每答对一题得3分，每答错一题扣2分．小红做完了10题，共得20分．请问小红答错了几道题？
<gadget id="calculator">10 * 3</gadget>
<output>30</output>

<gadget id="calculator">30 - 20</gadget>
<output>10</output>

<gadget id="calculator">3 + 2</gadget>
<output>5</output>

<gadget id="calculator">10 / 5</gadget>
<output>2</output>

<result>2</result>