The fourth grade collected 20.6 kilograms of medicinal materials, 2.4 kilograms more than the second grade. How many kilograms of medicinal materials were collected by the two classes?
四年级采集药材20.6千克，比二年级多采集2.4千克，两个班一共采集药材多少千克？
<gadget id="calculator">20.6 - 2.4</gadget>
<output>18.2</output>

<gadget id="calculator">18.2 + 20.6</gadget>
<output>38.8</output>

<result>38.8</result>