The fourth and fifth grade students collected tree species, the fourth grade collected 13.5 kilograms, and the fifth grade collected 2.8 kilograms less than the fourth grade. How many kilograms did the fourth and fifth grade students collect in total?
四、五年级同学采集树种，四年级采集了13.5千克，五年级比四年级少采集2.8千克，四、五年级同学一共采集多少千克？
<gadget id="calculator">13.5 - 2.8</gadget>
<output>10.7</output>

<gadget id="calculator">10.7 + 13.5</gadget>
<output>24.2</output>

<result>24.2</result>