There are 20 questions in a math competition. It is stipulated that 5 points will be awarded for 1 question that is correct, 3 points will be deducted for 1 question that is wrong, and no points will be given for questions that are not solved. Xiaohua has done all the questions in this competition, and the total score is 84 points. How many questions did he get right?
一次数学竞赛共20题，规定：做对1题给5分，做错1题不给分外还倒扣3分，不做的题不给分．小华在这次竞赛中全部题都做了，总分是84分．他做对了几道题？
<gadget id="calculator">20 * 5</gadget>
<output>100</output>

<gadget id="calculator">100 - 84</gadget>
<output>16</output>

<gadget id="calculator">5 + 3</gadget>
<output>8</output>

<gadget id="calculator">16 / 8</gadget>
<output>2</output>

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

<result>18</result>