Xiao Ming participated in a mathematics competition, and there were 20 competition questions in total. It is stipulated that 5 points will be awarded for each correct answer, and 2 points will be deducted for each wrong answer. Xiao Ming answered all 20 questions and got 86 points. How many questions did Xiao Ming answer correctly?
小明参加数学竞赛，共有20道赛题．规定答对一题给5分，答错一题倒扣2分．小明20题全部答完，得了86分．小明答对了多少题？
<gadget id="calculator">20 * 5</gadget>
<output>100</output>

<gadget id="calculator">100 - 86</gadget>
<output>14</output>

<gadget id="calculator">5 + 2</gadget>
<output>7</output>

<gadget id="calculator">14 / 7</gadget>
<output>2</output>

<gadget id="calculator">20 - 2</gadget>
<output>18</output>

<result>18</result>