The fourth grade of the Experimental Primary School held a mathematics competition. A total of 10 questions were asked, 10 points were awarded for each correct answer, and 5 points were deducted for each wrong answer. Zhang Hua finished all 10 questions and got 70 points. How many questions did he get right?
实验小学四年级举行数学竞赛，一共出了10道题，答对一题得10分，答错一题倒扣5分．张华把10道题全部做完，结果得了70分．他答对了几道题？
<gadget id="calculator">10 * 10</gadget>
<output>100</output>

<gadget id="calculator">100 - 70</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">10 - 2</gadget>
<output>8</output>

<result>8</result>