George has a total of B books in his library, 25 of which are hardcover fiction books. What is the value of B?

(1) 40 of the B books are fiction and the rest are nonfiction
(2) 60 of the B books are hardcovers and the rest are paperbacks
_________________

Is this E by any chance as we dont have sufficient info about Non fiction books

E for me too.

no info about Non-Fiction Paper back

IMO E
info given
f | Nf |total
HC|25|-
PB|- |-
A)
f | Nf |total
HC|25|-
PB|14|-
T |40|-
Clearly not sufficient
B)
f | Nf |total
HC|25|35|60
PB|--|-
T |--|-
Insufficient

A and B combined
f | Nf |total
HC|25|35|60
PB|15|??|
T |40|??|
Still value of nonfiction paper back is not known
there not sufficient
So E
_________________

IMO A...

What is the OA and OE?

Oh did a blunder!!

Now Got it!! Thanks Bunuel

In this kind of DS questions are fiction/non-fiction and hardcover/paperback options exhaustive? If there is no note that he has only these kinds of books, we can't assume it, right?

There are 4 categories of Books
P = Fiction & Hardcover
Q = Fiction & Paperback
R = Non-Fiction & Hardcover
S = Non-Fiction & Paperback

P+Q+R+S = B (given)
P = 25
Find Value of B

STMT 01: P+Q = 40
P=25 => Q = 15
P+Q+R+S = B
40+R+S = B
Since values of R & S are unknown. This stmt is insufficient.

STMT 02: P + R = 60
P=25 => R = 35
Q+S+60 = S
Since values of Q & S are unknow. This stmt is insufficient

STMT 01 & 02:
P=25 ; Q=15 ; R = 35 ; S = ?
P+Q+R+S = B
75+S = B
Still value of S is unknown. Hence E.

I completely agree that this question can be answered efficiently using a matrix box approach, also known as the double matrix. The one thing I want to add to this discussion is to answer the question: How do we know that we can use a matrix box on this question?

Whenever we see that a group can be divided into 2 parts in 2 different ways, we can use a matrix box. In this case, George's books can be divided into fiction and nonfiction (1st way) and hardcover and paperback (2nd way). This tells us that we can use a matrix box.

I hope that this helps others to more quickly recognize that a matrix box or double matrix will be useful on questions like these. If you want more practice on recognizing and using matrix boxes, please visit the following link, where I have compiled a list of questions on which you can use matrix boxes:

Matrix Boxes
_________________

How do I immediately see that the following matrix is not sufficient? I though I had enough equations to solve for B Bunuel?

_________________