Bryan School had 600 pupils and Japheth School had 25% less pupils. When an equal number of pupils joined each school, the ratio of the pupils in Japheth School to that in Bryan School became 5 : 4. How many pupils were there in both schools in the end?

	Bryan School	Japheth School	Difference
Before	600		150
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 Bryan School and Japheth School at first and in the end the same. 

Difference between the number of pupils in both schools at first
= 25% x 600
= ²⁵₁₀₀ x 600
= 150

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

1 u = 150

Total number of pupils in both schools in the end
= 5 u + 4 u
= 9 u
= 9 x 150
= 1350

Answer(s): 1350