The line graphs shows the average number of students in class I and II, average number of students in class III and II, average number of students in class I and III.
Note – Value of Z is equal to highest single digit perfect square number. Value of y is one less than the cube of an even prime number. Average number of students in class I and II in school A is ten less than the average number of students in class I and III of same school. Average number of students in class II and III in school C is five more than the average number of students in class I and II of same school.
Find the ratio of the total number of students in Class II of School B and School D together to the difference between the total number of students in Class III and Class I across all schools.