Walkabout

Each of the letters in the table above represents one of the numbers 1, 2, or 3, and each of these numbers occurs exactly once in each row and exactly once in each column. What is the value of r?
(1) v + z = 6
(2) s + t + u + x = 6
Solution:
Question Stem Analysis:
We need to determine the value of r given that every variable in the table represents one of the numbers 1, 2, or 3.
Statement One Alone:
This means both v and z are 3. Recall that each of the numbers occurs exactly once in each row and exactly once in each column, which means there is a “3” in the first row. Since v and z are 3, neither u nor x can equal 3 (otherwise we have a row with two 3’s). Thus, it must be true that r = 3. Statement one alone is sufficient.
Statement Two Alone:We see that 6 can be expressed as the sum of 1, 1, 2, and 2 or 1, 1, 1, and 3 if all addends have to be integers. However, since s and t are on the same row and u and x are on the same column, it must be the former; i.e. the sum of 1, 1, 2, and 2. Furthermore, it means one of the values of s and t is 1 and the other is 2. Lastly, since s and t are on the same row as r, r must be 3. (Alternatively, we can also argue that since one of the values of u and x is 1 and the other is 2 and they are on the same column as r, r must be 3). Statement two alone is sufficient.
Answer: D