There are 522 students in the upper grades of a school, which is three times the number of students in the middle grades. How many students are there in the upper grades than in the middle grades?
一个学校的高年级有学生522人，是中年级学生的3倍，高年级比中年级多多少人？
<gadget id="calculator">522 / 3</gadget>
<output>174</output>

<gadget id="calculator">522 - 174</gadget>
<output>348</output>

<result>348</result>