The fourth grade students collected 28 kilograms of tree species, the sixth grade collected more (2/7) than the fourth grade, and how many kilograms more tree species were collected in the sixth grade than in the fourth grade?
四年级同学收集树种28千克，六年级收集的比四年级多(2/7)，六年级比四年级多收集树种多少千克？
<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">28 * (2/7)</gadget>
<output>8</output>

<result>8</result>