Billy School had 615 students and George School had 40% less students. When an equal number of students joined each school, the ratio of the students in George School to that in Billy School became 4 : 3. How many students were there in both schools in the end?

	Billy School	George School	Difference
Before	615		246
Change	+ ?	+ ?
After	4 u	3 u	1 u

Since an equal number of students joined 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 Billy School and George School at first and in the end the same. 

Difference between the number of students in both schools at first
= 40% x 615
= ⁴⁰₁₀₀ x 615
= 246

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

1 u = 246

Total number of students in both schools in the end
= 4 u + 3 u
= 7 u
= 7 x 246
= 1722

Answer(s): 1722