The third grade is less than the fourth grade 13, and the fourth grade is less than the fifth grade by 22. In two sentences, it can be concluded that grade three is less than grade five 13+22=35.

Grade three+grade four+grade five = 126, and grade four and grade five are represented by grade three, that is, grade four = grade three+13.

Fifth grade = third grade +35 trees

So Grade Three+(Grade Three+13)+ (Grade Three +35)= 126.

3× Grade 3 +48= 126

Level 3 =( 126-48)÷3

You can get the following formula. The number of trees planted in the third grade is (126-13-13-22) ÷ 3 = 78 ÷ 3 = 26 (the reason for the formula has been mentioned earlier).

The fourth level is 26+ 13=39 trees.

The fifth level is 26+ 13+22=6 1 tree.

The answer is 26,39,61,please adopt it.