In section A the number of students boys and girls studying are in the ratio 3: 1. If the average weight of the whole class A is 14.25 and the average weight of the girls in class A is 12. If the number of boys in class B is x more than the number of boys in class A. Total number of students in class B is 50.Number of girls in class B is 10. Total weight of the boys in the class A is 450. Find the value of x.