Number Properties Guide 3rd Edition p.147

[jay.mathew]

1. I understand how statement 1 is sufficient.
Because, if c is negative, then a - b > 0
Thus, a > b
SUFFICIENT

2. Isn't statement 2 also sufficient?
I.e.
a + b < 0
a < -b
a > b
SUFFICIENT?

The answer in the guide is (A).

[StaceyKoprince]

a + b < 0
a < -b
a > b

Are you dividing by -1 to go from your second to last line to your last line? If so, you're missing one thing: if you divide by -1, you have to divide both sides by -1:

a < -b
-a > b

This allows multiple possibilities:
a = 2, b = -4 --> yes, a > b
a = -4, b = 2 --> no, a is not greater than b

[jay.mathew]

Thanks Stacey. My mistake...I can't believe I forgot to divide both sides. I must have been on an off day when I first posted that message. Sorry about this!!

[JonathanSchneider]

: )