Please explain this word problem.
A note book is made up of sheets folded in the middle and stapled, each sheet forms 2 leaves (i.e) 4 pages. On removing some papers of the first half and second half of the book, Joe found the number of leaves, in the first case as odd and in the second case as even. If the sum of the numbers of the pages on the last leaf of the book is 63,then what could be the maximum possible sum of the numbers on the pages of leaves that were left in book.
(1) 435 (2) 420 (3) 451 (4) 471..
Please explain clearly..(Crying)