Charlie School had 415 students and Jack School had 40% less students. When an equal number of students joined each school, the ratio of the students in Jack School to that in Charlie School became 4 : 3. How many students were there in both schools in the end?

	Charlie School	Jack School	Difference
Before	415		166
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 Charlie School and Jack School at first and in the end the same. 

Difference between the number of students in both schools at first
= 40% x 415
= ⁴⁰₁₀₀ x 415
= 166

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

1 u = 166

Total number of students in both schools in the end
= 4 u + 3 u
= 7 u
= 7 x 166
= 1162

Answer(s): 1162