Riordan School had 750 students and David School had 20% more students. When an equal number of students left each school, the ratio of the students in David School to that in Riordan School became 3 : 2. How many students were there in both schools in the end?

	Riordan School	David School	Difference
Before	750		150
Change	- ?	- ?
After	3 u	2 u	1 u

Since an equal number of students left each school, the difference in the number of students at first and in the end between the 2 schools remains the same.  Make the difference between the number of students in Riordan School and David School at first and in the end the same. 

Difference between the number of students in both schools at first
= 20% x 750
= ²⁰₁₀₀ x 750
= 150

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

1 u = 150

Total number of students in both schools in the end
= 3 u + 2 u
= 5 u
= 5 x 150
= 750

Answer(s): 750