The school organizes students to go to summer camps. There are 320 students in the first grade, 380 students in the second grade, and 160 students in the third grade than the total number of the first and second grades. How many students are there in the third grade?
学校组织学生去夏令营，一年级有320人，二年级有380人，三年级的人数比一、二年级的总人数少160人，三年级有多少人？
<gadget id="calculator">380 - 160</gadget>
<output>220</output>

<gadget id="calculator">320 + 220</gadget>
<output>540</output>

<result>540</result>