28 people participated in mathematics, English, and Chinese competitions. Each person participated in at least two competitions. 8 people did not participate in Chinese. The number of people who participated in mathematics and the number of people who participated in English and Chinese at the same time were 17. How many people only participated in mathematics and Chinese? people?
28人参加数学、英语、语文竞赛，每人至少参加两项竞赛，有8人未参加语文，参加数学的人数和同时参加英语和语文的人数都是17人，只参加数学和语文的有多少人？
<gadget id="calculator">17 - 8</gadget>
<output>9</output>

<gadget id="calculator">17 + 9</gadget>
<output>26</output>

<gadget id="calculator">28 - 8</gadget>
<output>20</output>

<gadget id="calculator">26 - 20</gadget>
<output>6</output>

<gadget id="calculator">9 - 6</gadget>
<output>3</output>

<result>3</result>