Yucai Primary School held the World Expo Knowledge Contest. There were 10 questions in total. It was stipulated that 6 points would be awarded for each correct answer, and 4 points would be deducted for each wrong answer. Xiaohua won a total of 30 points in this competition. How many questions did he answer correctly?
育才小学举行世博知识竞赛，共有10道题，规定每答对一题得6分，每答错一题倒扣4分，小华在这次竞赛中共得30分，他答对了几道题？
<gadget id="calculator">10 * 6</gadget>
<output>60</output>

<gadget id="calculator">60 - 30</gadget>
<output>30</output>

<gadget id="calculator">6 + 4</gadget>
<output>10</output>

<gadget id="calculator">30 / 10</gadget>
<output>3</output>

<gadget id="calculator">10 - 3</gadget>
<output>7</output>

<result>7</result>