Ian School had 430 pupils and Jack School had 10% more pupils. When an equal number of pupils left each school, the ratio of the pupils in Jack School to that in Ian School became 4 : 3. How many pupils were there in both schools in the end?

	Ian School	Jack School	Difference
Before	430		43
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 Ian School and Jack School at first and in the end the same. 

Difference between the number of pupils in both schools at first
= 10% x 430
= ¹⁰₁₀₀ x 430
= 43

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

1 u = 43

Total number of pupils in both schools in the end
= 4 u + 3 u
= 7 u
= 7 x 43
= 301

Answer(s): 301