The sub-duplicate ratio of 6x² : 24y² is :

1. x : 2y

2. 2x : y

3. x : y

4. y : x

A school has 630 students. The ratio of the number of boys to the number of girls is 3 : 2. This ratio changes to 7 : 5 after the admission of 90 new students. Find the number of newly admitted boys.