After one ninth of the number of class 52 was transferred to class 5.1, the number of class 1 was 75% of that of class 2

After one ninth of the number of class 52 was transferred to class 5.1, the number of class 1 was 75% of that of class 2

The original number of class 52 is regarded as unit "1"
Class 52 is open now
1-1 / 9 = 8 / 9
Class five one is available now
8 / 9 × 75% = 2 / 3
There used to be class five
2 / 3-1 / 9 = 5 / 9
What is the ratio of class two to class one
1: 5 out of 9 = 9:5

The number of girls in a class is less than two-thirds of the number of boys. If the number of girls increases by three and the number of boys decreases by three, then the number of girls is equal to nine times of the number of boys

Suppose boys have X, then girls have (2 / 3) X-2
It can be listed as follows:
[（2/3）x-2]+3＝（x-3）*（7/9）
X = 30 is the number of boys, girls have (2 / 3) X-2 = 18