Zane School had 480 pupils and Jeremy School had 25% less pupils. When an equal number of pupils joined each school, the ratio of the pupils in Jeremy School to that in Zane School became 5 : 4. How many pupils were there in both schools in the end?

	Zane School	Jeremy School	Difference
Before	480		120
Change	+ ?	+ ?
After	5 u	4 u	1 u

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

Difference between the number of pupils in both schools at first
= 25% x 480
= ²⁵₁₀₀ x 480
= 120

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

1 u = 120

Total number of pupils in both schools in the end
= 5 u + 4 u
= 9 u
= 9 x 120
= 1080

Answer(s): 1080