Peter School had 345 pupils and Henry School had 20% more pupils. When an equal number of pupils left each school, the ratio of the pupils in Henry School to that in Peter School became 4 : 3. How many pupils were there in both schools in the end?

	Peter School	Henry School	Difference
Before	345		69
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 Peter School and Henry School at first and in the end the same. 

Difference between the number of pupils in both schools at first
= 20% x 345
= ²⁰₁₀₀ x 345
= 69

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

1 u = 69

Total number of pupils in both schools in the end
= 4 u + 3 u
= 7 u
= 7 x 69
= 483

Answer(s): 483