Primary schools hold calligraphy exhibitions for students. Calligraphy works of students of all grades are displayed in the school window. Among them, 28 are not in the fifth grade and 24 are not in t

Primary schools hold calligraphy exhibitions for students. Calligraphy works of students of all grades are displayed in the school window. Among them, 28 are not in the fifth grade and 24 are not in the sixth grade. Because: (one+two+three+four+six) =28? ①

(one+two+three+four+five) =24? ②

From ①-②: 65 =4,

Because there are ***20 pictures in grade five and six, and there are (20-4)÷2=8 pictures in grade five;

Level 6: 20-8= 12 (frame);

So: (one+two+three+four) =24-8= 16 (amplitude);

Because: (one+two) +4= (three+four),

The calligraphy works exhibited in Grade One and Grade Two are: (16-4)÷2=6 (pieces);

A: There are 6 calligraphy works in Grade One and Grade Two.

So the answer is: 6.