The number of male students in the school's mathematics interest class accounts for three eighths of the total number of students in the mathematics interest class. Later, 20 male students joined. At this time, male students account for seven twelfth of the total number of students in the mathematics interest class?

The number of male students in the school's mathematics interest class accounts for three eighths of the total number of students in the mathematics interest class. Later, 20 male students joined. At this time, male students account for seven twelfth of the total number of students in the mathematics interest class?

Suppose there are x boys now
(x-20）/(3/5)=x/(7/5)
The solution is x = 35
The number of female students is 25

In the fifth grade mathematics interest group of a school, girls account for 3 out of 8, and then four girls are added, which is the number of girls just accounts for 9% of the whole group
Give me the solution

The number of girls in the fifth grade math interest group of a school accounts for 3 out of 8, and then four girls are added. This is that the number of girls just accounts for 4 out of 9 of the whole group. How many people are in the group now?
Boys are invariants, set as unit "1"
Originally, the number of boys was 5 / 8 of the whole group, but later, the number of boys was 5 / 9 of the whole group
Originally, the number of female students was 3 / 5 of that of male students. Later, the number of female students was 4 / 5 of that of male students,
So the number of boys is: 4 ÷ (4 / 5-3 / 5) = 20
Now the number of people in the group is: 20 / 5 / 9 = 36

In the school mathematics interest group, girls accounted for 2 / 5 of the whole group, and then there were 6 girls. In this way, the number of girls became 1 / 2 of the whole group. How many girls are there in this group? Can we use the sixth grade level to answer the questions?
Well Just can. Er. Write the whole process of the formula. Just write one answer. I don't know how to calculate

Suppose there are x girls, then the total number is x △ 2 / 5
Then came six, the number of girls is x + 6, the total number is (x + 6) △ 1 / 2
（X÷2/5+6）=(X+6)÷1/2
If x = 12, the number of girls in this group is 12 + 6 = 18

The number of male students in the school's mathematics interest class accounts for three eighths of the total number of students in the mathematics interest class. Later, 20 male students joined. At this time, male students account for seven twelfth of the total number of students in the mathematics interest class?

Now the total number is x, the original total number is x-20
Now boys x * 7 / 12, boys (x-20) * 3 / 8
x*7/12-（x-20）*3/8=20
x=60
Now boys 35, girls 25

1472-7 + 42 + 1 = 1414 + 111-11 and 27 × 4-12-24 = 12. The formula is formed by adding or removing a match
Yes, there are many rewards=

1472-1 (changed here, 7 changed to 1) + 42 + 1 = 1414 + 111-11
27 × 4-12-24 = 72

1472 minus 7 plus 42 plus 1 = 1414 plus 111 minus 11 plus a matchstick or minus a matchstick makes the formula true

1472 -7 +42+1=1414+111-11
Remove - from - 7, that is: - 1
1472 -1 +42+1=1414+111-11

2x444 + 12 = 24 remove a match to make the formula true

2x4+4+12=24

Use five nines to make the result equal to 10

9+9×9÷9÷9=10

Use five nines to make the result equal to 10. Write at least two formulas

(9+9-9)÷9+9=10
9x9÷9÷9+9=10