Answer: 11

Explanation: For 1:  

We have 6 books of Economics, 3 of Mathematics and 2 of Accountancy

Arranging the books within the branches:

Economics - 6!

Maths - 3!

Accountancy - 2!

Thus the arranging branches are 3!

Thus, total arrangement  

6!×3!×2!×3!=32,400

For 2: We have to add all the books together then arrange it

6+3+2=11

Thus the total arrangement are:

11!

39,916,800