Direction (): the data given below shows the information of total students in class A, B and C which are divided in three groups X, Y and Z.
Class A: Total no. of students are 90. 30 students are in group X. ratio of number of students in group Y and Z is 1: 2.
Class B: Total no. of students are 80. The ratio of no. of students in group X, Y and Z is 8: 5: 3.
Class C: the no. of students in group Y are half of that in group X. The no of students in group X of class C are 20 more than that in group X of class A. no. of students in group Z of class C are 20% less than that in group X of same class.