Hello, acc100jt!

Two problems:

[1] Is there a typo?

. . .Is the question "What fraction of Secondary2are girls?"

[2] The designations are far too confusing; I'll simplify the wording.

There are three classes:

The number of students in each of the three classes is the same.

The fraction of girls in is the same as the fraction of boys in

of all boys are in

What fraction of theBstudents are girls?

Let = number of students in each class.

"The fraction of girls in is the same as the fraction of boys in ."

. .[1]

The total number of boys is:

" of all boys are in "

. .

. . . . . . . . . . . . . .

From[1], we have: .

Therefore, of class B are girls.