Question 737642
1) First choose the order of the books subjects: 3 subjects so 3! Then arrange each subject: 4!6!2! So all together: 3!4!6!2!=207,360

2) First arrange the math books. there are 4! ways to do this. since they have to stay this way - together - consider the math subject now as 1 big "book", 6 physics boos and 2 chemistry books.

Then we have 1+6+2=9 "books" and can arrange them 9! ways. 

So we can have 4!9!=8,709,120 arrangements.