Xiao Qiang participated in the math competition, with 20 questions in total, 8 points for each correct answer, and 4 points deducted for each wrong answer. Xiao Qiang finally got 100 points. How many questions did he get right?
肖强参加了数学竞赛，共有20题，每做对一题可得8分，每做错一题倒扣4分，肖强最后得了100分，他做对了多少题．
<gadget id="calculator">20 * 8</gadget>
<output>160</output>

<gadget id="calculator">160 - 100</gadget>
<output>60</output>

<gadget id="calculator">8 + 4</gadget>
<output>12</output>

<gadget id="calculator">60 / 12</gadget>
<output>5</output>

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

<result>15</result>