The sixth grade students collected 42 kilograms of tree species, and the fifth grade collected less (2/7) than the sixth grade. How many kilograms of tree species did the fifth grade collect?
六年级同学收集树种42千克，五年级收集的比六年级少(2/7)，五年级收集树种多少千克？
<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">1 - (2/7)</gadget>
<output>5/7 = around 0.714286</output>

<gadget id="calculator">42 * (5/7)</gadget>
<output>30</output>

<result>30</result>