The students planted trees, the work efficiency ratio of the first group, the second group, and the third group was 5:3:4. The first group planted 15 trees, how many trees did the third group plant?
同学们植树，第一组、第二组、第三组的工作效率比是5：3：4．第一组植树15棵，第三组植树多少棵？
<gadget id="calculator">5 + 3 + 4</gadget>
<output>12</output>

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

<gadget id="calculator">15 / (5/12)</gadget>
<output>36</output>

<gadget id="calculator">4 / 12</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">36 * (1/3)</gadget>
<output>12</output>

<result>12</result>