The school allocated 536 books to each class according to the number of three classes in Grade 6. There are 45 students in class 1, 42 students in class 2 and 47 students in class 3. Each class should get more books There is another question that I hope primary schools can participate in tree planting activities. The ratio of trees planted in grade 4, 5 and 6 is 2:3:4. It is known that there are 84 more trees planted in Grade 6 than in grade 4. How many trees are planted in grade 4, 5 and 6?

The school allocated 536 books to each class according to the number of three classes in Grade 6. There are 45 students in class 1, 42 students in class 2 and 47 students in class 3. Each class should get more books There is another question that I hope primary schools can participate in tree planting activities. The ratio of trees planted in grade 4, 5 and 6 is 2:3:4. It is known that there are 84 more trees planted in Grade 6 than in grade 4. How many trees are planted in grade 4, 5 and 6?

45 + 42 + 47 = 134
536 × 45 / 134 = 180 class 1
536 × 42 / 134 = 168 class 2
536 × 47 / 134 = 188 class 3
2、2+3+4=9
84 ÷ (4 / 9-2 / 9) = 378 total
378 × 2 / 9 = 84 (trees) grade 4
378 × 3 / 9 = 126 fifth grade
378 × 4 / 9 = 168 sixth grade