There are 15 questions in the safety knowledge contest, 10 points will be awarded for one correct answer, and 5 points will be deducted for one wrong answer. Xiaoyun scored 120 points, how many questions did he answer correctly?
安全知识竞赛共15道题，答对一道题得10分，答错一道题倒扣5分．小云得了120分，他答对几道题？
<gadget id="calculator">15 * 10</gadget>
<output>150</output>

<gadget id="calculator">150 - 120</gadget>
<output>30</output>

<gadget id="calculator">10 + 5</gadget>
<output>15</output>

<gadget id="calculator">30 / 15</gadget>
<output>2</output>

<gadget id="calculator">15 - 2</gadget>
<output>13</output>

<result>13</result>