The third grade of Experimental Primary School held a mathematics competition with a total of 20 test questions. 5 points are awarded for a correct answer, and 3 points will be deducted for a wrong answer or an incorrect answer. Liu Gang scored 84 points. How many questions did he get right?
实验小学三年级举行数学竞赛，共20道试题．做对一题得5分，没有做一题或做错一题都要倒扣3分．刘钢得了84分，他做对了多少道题．
<gadget id="calculator">5 * 20</gadget>
<output>100</output>

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

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