There are 10 multiple-choice questions in a math competition. According to the grading rules, 2 points are awarded for a correct answer, and 3 points are deducted for a wrong answer. Xiaoxin answered 10 questions and scored 15 points. How many questions did she answer correctly?
一次数学竞赛有10道选择题，按照评分规定，答对一题得2分，答错一题倒扣3分，小欣回答了10道题，得了15分，她答对了几道题？
<gadget id="calculator">10 * 2</gadget>
<output>20</output>

<gadget id="calculator">20 - 15</gadget>
<output>5</output>

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

<gadget id="calculator">5 / 5</gadget>
<output>1</output>

<gadget id="calculator">10 - 1</gadget>
<output>9</output>

<result>9</result>