Albert School had 432 students and Ken School had 25% less students. When an equal number of students joined each school, the ratio of the students in Ken School to that in Albert School became 5 : 4. How many students were there in both schools in the end?

	Albert School	Ken School	Difference
Before	432		108
Change	+ ?	+ ?
After	5 u	4 u	1 u

Since an equal number of students joined each school, the difference in the number of students at first and in the end between the 2 schools remains the same.  Make the difference between the number of students in Albert School and Ken School at first and in the end the same. 

Difference between the number of students in both schools at first
= 25% x 432
= ²⁵₁₀₀ x 432
= 108

Difference between the number of students in both schools in the end
= 5 u - 4 u
= 1 u

1 u = 108

Total number of students in both schools in the end
= 5 u + 4 u
= 9 u
= 9 x 108
= 972

Answer(s): 972