Mark School had 780 pupils and Carl School had 25% more pupils. When an equal number of pupils left each school, the ratio of the pupils in Carl School to that in Mark School became 3 : 2. How many pupils were there in both schools in the end?

	Mark School	Carl School	Difference
Before	780		195
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 Mark School and Carl School at first and in the end the same. 

Difference between the number of pupils in both schools at first
= 25% x 780
= ²⁵₁₀₀ x 780
= 195

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

1 u = 195

Total number of pupils in both schools in the end
= 3 u + 2 u
= 5 u
= 5 x 195
= 975

Answer(s): 975