The three classes of the sixth grade need to plant 90 trees, the first class planted 3/10 of the total number of trees planted, the ratio of the number of trees planted by the second class to the third class is 5:4, how many trees are planted by the second class?
六年级三个班要植90棵树，一班种总数的(3/10)，二班、三班种的棵数比是5：4，二班种多少棵树？
<gadget id="calculator">3 / 10</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">1 - (3/10)</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">5 + 4</gadget>
<output>9</output>

<gadget id="calculator">5 / 9</gadget>
<output>5/9 = around 0.555556</output>

<gadget id="calculator">90 * (7/10) * (5/9)</gadget>
<output>35</output>

<result>35</result>