The safety of the people in the disaster area always affects the hearts of the students in Yishi, and they donate money for the children in the disaster area. The second grade students donated a total of 785 yuan, the third grade students donated 105 yuan more than the second grade students, and the fourth grade students donated twice as much as the sum of the second and third grade students' donations. How much does the fourth grade student donate?
灾区人民的安危时刻牵动着一实小同学们的心，他们纷纷为灾区儿童捐款．二年级学生共捐了785元，三年级的学生的捐款数比二年级多105元，四年级学生的捐款数是二、三年级学生的捐款数的总和的2倍．四年级学生捐款多少元？
<gadget id="calculator">785 + 785 + 105</gadget>
<output>1_675</output>

<gadget id="calculator">1_675 * 2</gadget>
<output>3_350</output>

<result>3_350</result>