Bunuel wrote:

The sum of the ages of Lindsey and Meghan is y, and Lindsey is exactly 9 years older than Meghan. Natalie is how many years older than Meghan?

(1) In y years, Meghan will be exactly three times as old as Natalie is now.

(2) Lindsey is exactly 6 years older than Natalie.

We can let L = Lindsay’s current age, M = Meghan’s current age, and N = Natalie’s current age. Thus:

L + M = y

L = y - M

and

L = M + 9

Adding L = y - M and L = M + 9, we have:

2L = y + 9

y = 2L - 9

So, we now have the following equations:

L = y - M, L = M + 9, and y = 2L - 9.

We need to determine the value of N - M.

Statement One Alone:

In y years, Meghan will be exactly three times as old as Natalie is now.

Using the information in statement one, we can create the following equation:

M + y = 3N

Since y = 2L - 9, we have:

M + 2L - 9 = 3N

Since L = M + 9, we have:

M + 2(M + 9) - 9 = 3N

M + 2M + 18 - 9 = 3N

3M + 9 = 3N

3 = N - M

Statement one alone is sufficient to answer the question.

Statement Two Alone:

Lindsey is exactly 6 years older than Natalie.

We can create the following equation:

L = 6 + N

Since L = M + 9, we have:

M + 9 = 6 + N

N - M = 3

Statement two alone is sufficient to answer the question.

Answer: D

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Jeffery Miller

Head of GMAT Instruction

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