Exercise 3. There are 15 questions in a chemistry competition held by a certain school. It is stipulated that every correct answer will get 10 points, and every wrong answer or no answer will deduct 4 points. Xiaohua scored 66 points in this competition. How many questions did he get right?
练习3，某校举行化学竞赛共有15道题，规定每做对一题得10分，每做错一道或不做倒扣4分．小华在这次竞赛中共得66分，他做对了几道题？
<gadget id="calculator">15 * 10</gadget>
<output>150</output>

<gadget id="calculator">150 - 66</gadget>
<output>84</output>

<gadget id="calculator">10 + 4</gadget>
<output>14</output>

<gadget id="calculator">84 / 14</gadget>
<output>6</output>

<gadget id="calculator">15 - 6</gadget>
<output>9</output>

<result>9</result>