Sean School had 620 pupils and Daniel School had 20% more pupils. When an equal number of pupils left each school, the ratio of the pupils in Daniel School to that in Sean School became 3 : 2. How many pupils were there in both schools in the end?

	Sean School	Daniel School	Difference
Before	620		124
Change	- ?	- ?
After	3 u	2 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 Sean School and Daniel School at first and in the end the same. 

Difference between the number of pupils in both schools at first
= 20% x 620
= ²⁰₁₀₀ x 620
= 124

Difference between the number of pupils in both schools in the end
= 3 u - 2 u
= 1 u

1 u = 124

Total number of pupils in both schools in the end
= 3 u + 2 u
= 5 u
= 5 x 124
= 620

Answer(s): 620