Xavier School had 605 students and Mark School had 20% more students. When an equal number of students left each school, the ratio of the students in Mark School to that in Xavier School became 2 : 1. How many students were there in both schools in the end?

	Xavier School	Mark School	Difference
Before	605		121
Change	- ?	- ?
After	2 u	1 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 Xavier School and Mark School at first and in the end the same. 

Difference between the number of students in both schools at first
= 20% x 605
= ²⁰₁₀₀ x 605
= 121

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

1 u = 121

Total number of students in both schools in the end
= 2 u + 1 u
= 3 u
= 3 x 121
= 363

Answer(s): 363