What is the respective ratio of students studying in class IX of schools Q and R together to those studying in class VI of schools S and T together?

Total number of students of class IX of schools Q and R = Total number of students of class IX of (Schools Q + school R)
Total number of students of class IX of schools Q and R = 157 + 143 = 300
Total number of students of class VI of schools S and T = Total number of students of class VI of ( School S + School T)
Total number of students of class VI of schools S and T = 142 + 144 = 286
Hence, required ratio = 300 : 286 = 150 : 143