Oliver School had 616 pupils and Ivan School had 25% more pupils. When an equal number of pupils left each school, the ratio of the pupils in Ivan School to that in Oliver School became 2 : 1. How many pupils were there in both schools in the end?

	Oliver School	Ivan School	Difference
Before	616		154
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 Oliver School and Ivan School at first and in the end the same. 

Difference between the number of pupils in both schools at first
= 25% x 616
= ²⁵₁₀₀ x 616
= 154

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

1 u = 154

Total number of pupils in both schools in the end
= 2 u + 1 u
= 3 u
= 3 x 154
= 462

Answer(s): 462