In a mathematics test, the scores of the four students were 76 points, x points, 86 points, and 92 points. Their average score is 86, what is the score of the students whose grades are unknown.
一次数学考试，4名同学的分数分别是76分、x分、86分、92分．他们的平均分是86，成绩未知的同学是多少分．
<gadget id="calculator">86 * 4</gadget>
<output>344</output>

<gadget id="calculator">76 + 86 + 92</gadget>
<output>254</output>

<gadget id="calculator">344 - 254</gadget>
<output>90</output>

<result>90</result>