Japheth School had 450 pupils and Daniel School had 30% more pupils. When an equal number of pupils left each school, the ratio of the pupils in Daniel School to that in Japheth School became 2 : 1. How many pupils were there in both schools in the end?

	Japheth School	Daniel School	Difference
Before	450		135
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 Japheth School and Daniel School at first and in the end the same. 

Difference between the number of pupils in both schools at first
= 30% x 450
= ³⁰₁₀₀ x 450
= 135

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

1 u = 135

Total number of pupils in both schools in the end
= 2 u + 1 u
= 3 u
= 3 x 135
= 405

Answer(s): 405