Answer:
He needs to build 38 shelves
Explanation:
The number of books that can be accommodated in one shelf = 34
Total number of books in the book store = 1265
Dividing the total number of books by number of books per shelf will yield the total number of shelves needed, i.e

Putting the values,

As the number of shelves can not be in fraction, so total number of shelves needed will be 38.