Students in two classes in the fifth grade collected tree species. The first class had 47 students, and each person collected 0.25 kilograms. The second class, with 45 students, collected a total of 10.15 kilograms. How many kilograms of tree species were collected by the two classes?
五年级两个班的学生采集树种，一班47人，每人采集了0.25千克，二班45人共采集10.15千克，两个班一共采集树种多少千克？
<gadget id="calculator">0.25 * 47</gadget>
<output>11.75</output>

<gadget id="calculator">11.75 + 10.15</gadget>
<output>21.9</output>

<result>21.9</result>