There are 213 students in the fourth grade, and 205 students in the third grade are twice as many as the fourth grade. How many people are there in the third and fourth grades?
学校四年级有213人，三年级的人数是四年级的2倍少205人．三、四年级一共有多少人？
<gadget id="calculator">213 * 2</gadget>
<output>426</output>

<gadget id="calculator">426 - 205</gadget>
<output>221</output>

<gadget id="calculator">221 + 213</gadget>
<output>434</output>

<result>434</result>