There are 20 questions in a math competition. It is stipulated that if you answer a question correctly, you will get 5 points. How many questions did you answer?
一次数学竞赛共20道题，规定做对一道题得5分，做错一道倒扣3分，不做的不得分，小明在这次竞赛中全部题都做了，得了84分，他做对了多少道题．
<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>

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

<result>18</result>