The students donated a total of 6,400 yuan to the disaster area for the third and fourth graders. It is more than the first and second grades (1/7). How much is the total donation for the first and second grades?
同学们向灾区捐款三四年级共捐款6400元．比一二年级多(1/7)，一二年级共捐款多少元？
<gadget id="calculator">1 / 7</gadget>
<output>1/7 = around 0.142857</output>

<gadget id="calculator">1 + (1/7)</gadget>
<output>8/7 = around 1.142857</output>

<gadget id="calculator">200 / (8/7)</gadget>
<output>175</output>

<result>175</result>