Data Sufficiency

Q20:
Favorable Unfavorable Not Sure
Candidate M 40 20 40
Candidate N 30 35 35
The table above shows the results of a survey of 100 voters each responded “favorable”
or “unfavorable” or “not sure” when asked about their impressions of candidate M and of
candidate N. What was the number of voters who responded “favorable” for both
candidates?
(1) The number of voters who did not respond “favorable” for either candidate was
40.
(2) The number of voters who responded “unfavorable” for both candidates was 10.
A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is
sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.
Answer:

Dear Saurabh
Combine the UF and NS into one. So we have the following grid

Mfav Motherwise Ntotal
N fav x 30
N otherwise w y 70
Mtotal 40 60 100

Now, Motherwise and Notherwise is given as 40 i.e. y=40
=> w= 30 => x = 10
So, 1 is sufficient.
2 does not give any data for excluding Favourable so can't be solved
Hence, answer is (A). At least, that is what I think
Cheers