Three young pioneers planted 100 trees. A planted 2/5 of the total number of trees. The ratio of the number of trees planted by plant B to plant C was 7:5. How many trees did plant C plant less than plant B?
三个少先队员种了100棵树，甲种了总数的(2/5)，乙与丙种的棵数比是7：5，丙比乙少种了多少棵？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">100 * (2/5)</gadget>
<output>40</output>

<gadget id="calculator">100 - 40</gadget>
<output>60</output>

<gadget id="calculator">7 + 5</gadget>
<output>12</output>

<gadget id="calculator">7 / 12</gadget>
<output>7/12 = around 0.583333</output>

<gadget id="calculator">60 * (7/12)</gadget>
<output>35</output>

<gadget id="calculator">5 / 12</gadget>
<output>5/12 = around 0.416667</output>

<gadget id="calculator">60 * (5/12)</gadget>
<output>25</output>

<gadget id="calculator">35 - 25</gadget>
<output>10</output>

<result>10</result>