The two classes of the sixth grade donated 2800 yuan to the "Hope Project". The ratio of donations from class one to class two was 3:4. How much less did class one donate than class two?
六年级两个班为"希望工程"捐款2800元，一班与二班捐款钱数的比是3：4，一班比二班少捐款多少元？
<gadget id="calculator">3 + 4</gadget>
<output>7</output>

<gadget id="calculator">2_800 / 7</gadget>
<output>400</output>

<gadget id="calculator">400 * 4</gadget>
<output>1_600</output>

<gadget id="calculator">400 * 3</gadget>
<output>1_200</output>

<gadget id="calculator">1_600 - 1_200</gadget>
<output>400</output>

<result>400</result>