There are 400 more students in the first grade than in the sixth grade, and (2/5) the number of students in the first grade is equivalent to (10/17) in the sixth grade. How many students are there in the two grades?
一年级比六年级学生数多400人，一年级人数的(2/5)相当于六年级的(10/17)，两个年级共多少人？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(2/5) * 400</gadget>
<output>160</output>

<gadget id="calculator">10 / 17</gadget>
<output>10/17 = around 0.588235</output>

<gadget id="calculator">(10/17) - (2/5)</gadget>
<output>16/85 = around 0.188235</output>

<gadget id="calculator">160 / (16/85)</gadget>
<output>850</output>

<gadget id="calculator">850 + 400 + 850</gadget>
<output>2_100</output>

<result>2_100</result>