Students from Qianlou Central Primary School used Sunday to collect tree species. They collected 2.8 kilograms in the first week, and 0.3 kilograms less in the second week than in the first week. How many kilograms did they collect in two weeks?
前楼中心小学的同学利用周日采集树种，第一周采集2.8千克，第二周采集的比第一周少0.3千克，两周一共采集了多少千克？
<gadget id="calculator">2.8 - 0.3</gadget>
<output>2.5</output>

<gadget id="calculator">2.5 + 2.8</gadget>
<output>5.3</output>

<result>5.3</result>