There are 20 questions in the math competition, 5 points are awarded for one correct answer, 2 points are deducted for one incorrect answer, Xiaoguang has completed all the questions, and has a total of 72 points. How many questions did he get right?
数学竞赛出了20道题，做对一道得5分，做错一道扣2分，小光做完了所有的题，共得72分，他做对了多少道题？
<gadget id="calculator">5 * 20</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>