magazine is priced at 2.50 yuan per issue, and a total of 12 issues are published throughout the year. Some students in a certain class book for half a year, and other students book for a whole year. The total subscription fee is 1320 yuan; How many students are there in this class?
某杂志社每期定价2.50元，全年共出12期．某班一些学生订半年，其余学生订全年，共需订费1320元；如果订全年的改订半年，而订半年的改订全年，共需订费1245元．这个班共有多少名学生．
<gadget id="calculator">1_320 + 1_245</gadget>
<output>2_565</output>

<gadget id="calculator">2_565 / 1.5</gadget>
<output>1_710</output>

<gadget id="calculator">2.5 * 12</gadget>
<output>30</output>

<gadget id="calculator">1_710 / 30</gadget>
<output>57</output>

<result>57</result>