Three classes of the sixth grade in a certain school planted trees. The number of trees planted in the first class accounted for (2/5) of the total number of the three classes, and the number of trees planted in the second class was that of the third class (3/7). The number of trees planted in the second class was 24 less than that of the third class. How many trees were planted by these three classes?
某校六年级三个班植树，一班植树的棵树占三个班总数的(2/5)，二班的棵数是三班的(3/7)，二班比三班少植树24棵，这三个班共植树多少棵？
<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">1 - (3/7)</gadget>
<output>4/7 = around 0.571429</output>

<gadget id="calculator">24 / (4/7)</gadget>
<output>42</output>

<gadget id="calculator">42 * (3/7)</gadget>
<output>18</output>

<gadget id="calculator">42 + 18</gadget>
<output>60</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">60 / (3/5)</gadget>
<output>100</output>

<result>100</result>