There are 20 questions in the fifth grade mathematics competition. It is stipulated that if you answer a question correctly, you will get 5 points, and if you get a wrong question, 3 points will be deducted. Wang Ming scored 84 points in this competition. How many questions did he get wrong?
五年级数学竞赛共20道题，规定做对一题得5分，做错一题倒扣3分，王明在这次竞赛中得了84分，他做错了几道题？
<gadget id="calculator">20 * 5</gadget>
<output>100</output>

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

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

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

<result>2</result>