If x - y > 10, Is x - y

[enniguy]

If x - y > 10, Is x - y > x + y ?

(1) x = 8
(2) y = -20

Source: GMATPrep 2. Could someone please explain the answer to this question?

[agha79]

If x - y > 10, Is x - y > x + y ?

(1) x = 8
(2) y = -20
================

Question tells us that x - y > 10.

Statement I:
Tells us X is 8. In order for X - Y > 10 to be true Y must be negative number less than negative two or (y < -2). This will always yield x - y > x + y so Statement I is sufficient.

Statement II:
Tells us Y is -20. In order for X - Y > 10 as given in the question X must be greater than negative ten or (X > -10). This will always yield x - y > x + y so Statement II is sufficient.

IMO Both statements are independently sufficient and correct answer should be "D"
Can you please post the OA:

[geetesht]

If x - y > 10, Is x - y > x + y ?

(1) x = 8
(2) y = -20
================

Question tells us that x - y > 10.

Statement I:
Tells us X is 8. In order for X - Y > 10 to be true Y must be negative number less than negative two or (y < -2). This will always yield x - y > x + y so Statement I is sufficient.

Statement II:
Tells us Y is -20. In order for X - Y > 10 as given in the question X must be greater than negative ten or (X > -10). This will always yield x - y > x + y so Statement II is sufficient.

IMO Both statements are independently sufficient and correct answer should be "D"
Can you please post the OA:

agha , i got the same answer good work ! btw enniguy wats the OA ??

[ai42]

The question can actually be simplified.
Is x - y > x + y ? is the same as
is 2y<0, or is y<0.
So, the answer is given in 2)
OA is b)

[Ben Ku]

The question can actually be simplified.
Is x - y > x + y ? is the same as
is 2y<0, or is y<0.
So, the answer is given in 2)
OA is b)

This is the right approach, but wrong answer. We can indeed rephrase the question as "Is y < 0?".

Statement (2) obviously answers the question, and is therefore sufficient.

Statement (1) says that x = 8. The question stem says that x - y > 10. We can substitute it in:
8 - y > 10 --> y < -2

This means that y is definitely negative, so (1) is sufficient as well.

The answer should be (D).