Student Liu Chang went to participate in a math competition. There were 20 questions in total, 5 points were awarded for a correct one, and 2 points were deducted for a wrong one. As a result, Liu Chang scored 72 points in the test. How many questions did he get right?
刘畅同学去参加数学竞赛，共有20道题，做对一道得5分，做错一道题倒扣2分．结果刘畅同学考了72分，问他做对了几道题？
<gadget id="calculator">20 * 5</gadget>
<output>100</output>

<gadget id="calculator">100 - 72</gadget>
<output>28</output>

<gadget id="calculator">5 + 2</gadget>
<output>7</output>

<gadget id="calculator">28 / 7</gadget>
<output>4</output>

<gadget id="calculator">20 - 4</gadget>
<output>16</output>

<result>16</result>