Ryan School had 610 pupils and Ahmad School had 10% more pupils. When an equal number of pupils left each school, the ratio of the pupils in Ahmad School to that in Ryan School became 4 : 3. How many pupils were there in both schools in the end?

	Ryan School	Ahmad School	Difference
Before	610		61
Change	- ?	- ?
After	4 u	3 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 Ryan School and Ahmad School at first and in the end the same. 

Difference between the number of pupils in both schools at first
= 10% x 610
= ¹⁰₁₀₀ x 610
= 61

Difference between the number of pupils in both schools in the end
= 4 u - 3 u
= 1 u

1 u = 61

Total number of pupils in both schools in the end
= 4 u + 3 u
= 7 u
= 7 x 61
= 427

Answer(s): 427