In the tree planting activities, each student in Grade 6 plants 8.5 trees on average. If men and women are calculated separately, then boys plant 10 trees on average and girls plant 6 trees on average. What percentage of the total number of girls in this grade? fast

In the tree planting activities, each student in Grade 6 plants 8.5 trees on average. If men and women are calculated separately, then boys plant 10 trees on average and girls plant 6 trees on average. What percentage of the total number of girls in this grade? fast

There are x boys and y girls,
8.5（x+y）=10x+6y,
8.5x+8.5y=10x+6y,
1.5x=2.5y,
3x=5y,
x：y=5：3,
Therefore, female students account for 37.5% of the total number of students in the class

A total of 100 students from grade 6 participated in the tree planting activities. Three boys and five girls planted one tree. A total of 30 trees were planted. How many boys and girls participated in the activities
It is suggested that 1 △ 3 = 1 / 3, 1 △ 5 = 1 / 5

100 △ 5 = 20 (person)
30-20 = 10
10 ÷ (5-3) = 5 (person)
20 + 5 = 25 (person)
100-25 = 75 (person)
A: there are 75 boys and 25 girls

In the tree planting activities of a class with boys accounting for the total number of students in the class, the average person plants trees in 7.5 classes. If the men and women are calculated separately, the average number of trees planted by boys is 9, and that of girls is 5. What is the percentage?

If you can turn on the phone, the mobile phone customer will say something very embarrassing. I feel the opportunity to go back to the room number

On Sunday, Xiao Ming and seven classmates, a total of 8 people, went on an outing. On the way, he spent 20 yuan to buy drinks. The store only had coke and milk tea. It is known that coke costs 2 yuan a cup and milk tea costs 3 yuan a cup. If 20 yuan is just used up. (1) how many ways to buy? How many cups of cola and milk tea in each way? (2) When each person has at least one drink and at least two milk teas, how many ways to buy them?

(1) Let's buy Coke and milk tea as X and Y cups respectively. According to the meaning of the question, we get 2x + 3Y = 20 (and X and y are natural numbers) 2x = 20-3y, x = 10-32y ∧ x = 10Y = 0, x = 7Y = 2, x = 4Y = 4, x = 1y = 6. So there are four ways to buy Coke and milk tea. The number of cups of coke and milk tea in each way is ① 10, 0; ② 7, 2; ③ 4, 4; ④ 1, 6; (2) according to the meaning of the question, when each person has at least one drink and milk tea has at least two cups According to (1), there are two ways to buy: ① 7, 2; ② 4, 4