Xiao Ming scored 86 points in a math competition. There were 20 questions in this competition, 5 points for a correct one, 2 points for a wrong one and no answer, how many questions Xiao Ming got right.
小明在一次数学比赛中得了86分，这次比赛一共有20道题，正确一道得5分，错一道和不做扣2分，小明正确多少道道．
<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>