How many students are in class?

Question

there are two classes.Class A has 18 more students than class B.If 1/8 of class B, both classes would have the same number of students.

Answer 1

If the question is "If 1/8 of class A moves to class B, ..." then the solution is  

 

A has 18 more than B  ==>  A = B + 18

 

If 1/8 of class A moves to class B then the new class A will have (7/8)*A left and the new class B will have B + (1/8)*A.  If these two are equal then  

 

(7/8)*A = B + (1/8)*A 

(6/8)*A = B

 

Substitute this value for B into the 1st equation  

 

A = (6/8)*A + 18

(2/8)*A = 18

A = 18*4 = 72 

 

So B = 72 - 18 = 54 

 

There are 72 students in class A and 54 students in class B 

 

Check:  72 - 54 = 18 

            (1/8) of 72 is 9.  72 - 9 = 63.  54 + 9 = 63.