A. There are 84 students in class B and 58 students in 8 / 5 of class A and 4 / 3 of class B, so there are () students in class A There can only be one unknown number. Let a be x and B be (84 - x)

A. There are 84 students in class B and 58 students in 8 / 5 of class A and 4 / 3 of class B, so there are () students in class A There can only be one unknown number. Let a be x and B be (84 - x)

Let a be x, then B be (84-x)
8/5X+4/3(84-X)=58
8/5X+63-4/3X=58
-8/1X=-5
X=40
So the number of class B is 84-40 = 54
A: there are 40 in class A and 54 in class B