There are 20 multiple-choice questions in the mathematics competition, 5 points are awarded for 1 correct answer, and 1 point is deducted for wrong answer or no answer. Xiao Wang scored 82 points in the competition, how many questions did he answer correctly?
数学竞赛共有20道选择题，答对1题得5分，答错或不答倒扣1分．小王同学在竞赛中得了82分，他答对多少道题．
<gadget id="calculator">20 * 5</gadget>
<output>100</output>

<gadget id="calculator">100 - 82</gadget>
<output>18</output>

<gadget id="calculator">5 + 1</gadget>
<output>6</output>

<gadget id="calculator">18 / 6</gadget>
<output>3</output>

<gadget id="calculator">20 - 3</gadget>
<output>17</output>

<result>17</result>