The Young Pioneers participated in the tree planting activity. The first team of Class 1 planted 4 rows of trees, 15 trees in each row. The second team also planted some trees. Now there are 105 trees in total. How many trees did the second team plant?
少先队员参加植树活动，六1班第一小队种4行树，每行15棵．第二小队也种了一些树，现在共有105棵树，第二小队种了多少棵树？
<gadget id="calculator">4 * 15</gadget>
<output>60</output>

<gadget id="calculator">105 - 60</gadget>
<output>45</output>

<result>45</result>