Students collect tree species. The fifth grade collected 30 kilograms, which is less (2/7) than the sixth grade. How many kilograms did the sixth grade collect?
同学们收集树种．五年级收集了30千克，比六年级收集的少(2/7)，六年级收集了多少千克？
<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">30 / (5/7)</gadget>
<output>42</output>

<result>42</result>