Hi All,
While this question is wordy, and will require some note-taking, it can be solved by TESTing VALUES.
Let's TEST...
R = 5 students
Y = 50 dollars
X = 3 fail to pay
So the 'story' is that 5 students agree to pay an equal amount for a $50 present (that's $10 per student). We're told that 3 of them fail to pay (3 students x $10/each = $30 unpaid). Thus, the remaining 2 students have to pay an extra $30/2 = $15 each for the present.
Thus, we're looking for an answer that equals 15 when R=5, Y=50 and X=3
While the answer choices look complex, there are some patterns involved: several of the calculations repeat (for example, R-X appears in 4 of the answers, so you do NOT need to calculate it 4 separate times). Since Y = 50, any answer with Y alone in the numerator can be skipped over (there is no integer that will make 50/integer = 15). That leaves two answers to TEST and just a bit of arithmetic.
Final Answer:
GMAT assassins aren't born, they're made
Rich