In June, Class 4 and Class 1 collected 7.5 kg of waste paper, which was 0.7 kg less than Class 4 and Class 2. How many kg of waste paper were collected by the two classes?
六月份四1班收集废纸7.5千克，比四2班少收集0.7千克，两个班一共收集废纸多少千克？
<gadget id="calculator">7.5 + 0.7</gadget>
<output>8.2</output>

<gadget id="calculator">8.2 + 7.5</gadget>
<output>15.7</output>

<result>15.7</result>