The number of girls in class 6 (1) originally accounted for 3 / 4 of the boys. After the beginning of school, two girls were transferred to class 6 (1). At this time, girls accounted for 5 / 11 of the class?

The number of girls in class 6 (1) originally accounted for 3 / 4 of the boys. After the beginning of school, two girls were transferred to class 6 (1). At this time, girls accounted for 5 / 11 of the class?

Suppose that the number of boys is x, the number of girls is (3 / 4) x, and the number of girls is (3 / 4) x + 2
Then (3 / 4) x + 2 = 5 / 11 ((3 / 4) x + 2 + x)
The result is 33x + 88 = 15x + 40 + 20x
And x = 24
The original number is: x + (3 / 4) x = 24 + 18 = 42

Six for one pendulum, 11 for two, 16 for three, and () for 20?

Formula: n * 5 + 1
20 is 101

There is a saying that "seven mountains, one water and two fields" in a certain place, which means that the area ratio of mountains, water and fields in this place is 7:1:2,
The total area of land in this area is 96000 square kilometers. How large is the mountainous area in this area?

9.6 * (7 / (7 + 1 + 2)) = 67200 square kilometers