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