OG answer might be wrong -

Hi amogha_cs21,

We're told that Pat SAVED $600 of his earnings last month. We're asked how much Pat EARNED last month.

1) Pat spent 1/2 of his earnings last month for living expenses and saved 1/3 of the remainder.

Since we already know that Pat SAVED $600 last month, we can 'work backwards' based on the information in Fact 1 to determine how much Pat earned:

If 1/3 of X = $600, then X = ($600)(3) = $1800, so $1800 was what Pat had AFTER living expenses....
1/2 of Y = $1800, so Y = ($1800)(2) = $3600, so Pat EARNED $3600 last month.

Working forward, you can double-check this result if you like - and you'll see that it 'fits' all of the information that we've been given and answers the question.
Fact 1 is SUFFICIENT

2) Of his earnings last month, Pat paid twice as much in taxes as he saved.

The information in Fact 2 tells us that Pat TWICE as much in taxes as the $600 that we know that Pat saved. Unfortunately, there's no way to determine how much Pat actually EARNED, since neither the amount saved nor the amount paid in taxes is given a 'relationship' to the amount earned.
Fact 2 is INSUFFICIENT

Final Answer: A

GMAT assassins aren't born, they're made,
Rich

[email protected] wrote:

If Pat saved $600 of his earnings last month, how
much did Pat earn last month?
(1) Pat spent 1/2 of his earnings last month for living
expenses and saved 1/3 of the remainder.
(2) Of his earnings last month, Pat paid twice as
much in taxes as he saved.

In the DS question , I chose D,
However the OG states that the answer is
Th e correct answer is A;
statement 1 alone is sufficient.

Please explain ?
Because if you consider earnings as x
x=600+600*2
why is A the answer?

Make sure that you're not assuming that the categories given are COMPREHENSIVE. For example, I could take my earnings and save some of it, pay some of it in taxes, spend some of it on food, give some away to charity... so savings + taxes might not add up to the total earnings.

If we were told about "the amount he saved" and "the amount he didn't save," we can infer that these two add up to the entire total. But we can't assume that any other two categories are comprehensive. You should always ask yourself: could there be a 3rd category?