The fourth and fifth graders collected tree species, and the fourth grade collected 13.5 kilograms, which was 3.6 kilograms less than the fifth grade. How many kilograms did the fourth and fifth graders collect in total?
四、五年级同学采集树种，四年级采集了13.5千克，比五年级少采集3.6千克，四、五年级同学一共采集多少千克？
<gadget id="calculator">13.5 + 3.6 + 13.5</gadget>
<output>30.6</output>

<result>30.6</result>