Justin School had 556 students and Elijah School had 25% less students. When an equal number of students joined each school, the ratio of the students in Elijah School to that in Justin School became 5 : 4. How many students were there in both schools in the end?

	Justin School	Elijah School	Difference
Before	556		139
Change	+ ?	+ ?
After	5 u	4 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 Justin School and Elijah School at first and in the end the same. 

Difference between the number of students in both schools at first
= 25% x 556
= ²⁵₁₀₀ x 556
= 139

Difference between the number of students in both schools in the end
= 5 u - 4 u
= 1 u

1 u = 139

Total number of students in both schools in the end
= 5 u + 4 u
= 9 u
= 9 x 139
= 1251

Answer(s): 1251