60 kilograms of second-class apples, that is, 60/3 * 20=400 yuan,

Equivalent to 1000/ 120=50/6,

That is, 50/6 yuan per kilogram of apples,

The next day, each basket of first-class apples weighed 30 Jin, and so did the second-class apples.

40 yuan is 5 kilograms, so one kilogram is 40/5=8 yuan.

Obviously, the apples I bought the next day were 50/6-8= 1/3 yuan less per kilogram than the first day.

The total * * * is still 120kg, so it is 120* 1/3=40 yuan.

That is, 1000-960=40 yuan.

I wish I could help you,