Find the number of students above twelve years of age in your class. Then, find the ratio of number of students with age above twelve years and the remaining students.
Total number of students in my class = $$50$$
Total number of students above $$12$$ years of age = $$30$$
Ratio of number of students with age above twelve years and the remaining students = $$30$$ : $$20$$ = $$3$$ : $$2$$