Fill the boxes using (1, 3, 5, 7, 9, 11, 13, 15)

Solve this..
◻➕◻➕◻➕◻➕◻=30
Fill the boxes using (1, 3, 5, 7, 9, 11, 13, 15)
U can also repeat the numbers..
This question came in UPSC Final Exams held in Dec '13......
You will be glad to note that only Gaurav Agarwal could solve it.
Possible Solutions to Fill the boxes Puzzle :
Solution 1 :
(15-9)+(13-7)+(7-1)+(9-1)+(13-9)=30
so from the solution we can get
6+6+6+8+4 = 30
Solution 2 :
3weeks+7days+11hrs+13hrs+1days = 30day
Solution 3 :
3!+3!+3!+3!+3!=30