Hi ziyuenlau,
We're told that X must be an INTEGER, so since we're adding the sums of 3 absolute values - AND we're looking for sums that are LESS than or EQUAL to 11 - there can only be a limited number of possible solutions. Based on the answer choices, we know that there are at least 2, but no more than 12, possible integer values for N. As such, we can use a bit of 'brute force' to find all of the possible values without too much trouble.
We're given the inequality: |X - 3| + |2X + 4| + |X| ≤ 11
Let's start with...
X = 0.... |-3| + |4| + |0| = 7 so X could be 0
Now let's work our way "up"...
X = 1.... |-2| + |6| + |1| = 9 so X could be 1
X = 2.... |-1| + |8| + |2| = 11 so X could be 2
X = 3.... |0| + |10| + |3| = 13 so X CANNOT be 3
Increasing X will just increase the total further, so there's no reason to test any additional positive integers...
Now let's work our way "down"....
X = -1.... |-4| + |2| + |-1| = 7 so X could be -1
X = -2.... |-5| + |0| + |-2| = 7 so X could be -2
X = -3.... |-6| + |-2| + |-3| = 11 so X could be -3
X = -4.... |-4| + |-4| + |-4| = 12 so X CANNOT be -4
Decreasing X will just increase the total further, so there's no reason to test any additional negative integers...
We have 6 possible values of X.
Final Answer: A
GMAT assassins aren't born, they're made,
Rich