Liam School had 765 pupils and Dylan School had 20% more pupils. When an equal number of pupils left each school, the ratio of the pupils in Dylan School to that in Liam School became 2 : 1. How many pupils were there in both schools in the end?

	Liam School	Dylan School	Difference
Before	765		153
Change	- ?	- ?
After	2 u	1 u	1 u

Since an equal number of pupils left 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 Liam School and Dylan School at first and in the end the same. 

Difference between the number of pupils in both schools at first
= 20% x 765
= ²⁰₁₀₀ x 765
= 153

Difference between the number of pupils in both schools in the end
= 2 u - 1 u
= 1 u

1 u = 153

Total number of pupils in both schools in the end
= 2 u + 1 u
= 3 u
= 3 x 153
= 459

Answer(s): 459