Is |x-y| > |x|-|y|?

[ASMAA997]

see the question in the title , then,

A ) Y<X
B ) xy<0

this question from Gmat prep.
My questions are :
1- Is how to reach the right solution
2- To be more specific, In data sufficiency how do we find the right answers if in the choices is given as variables ?!

Given answer B

[RonPurewal]

please do NOT just post a problem and say "how do i solve this?". you need to ask SPECIFIC questions!

you probably STARTED the problem in some way... and then got stuck at some SPECIFIC point(s) along the way.
assuming that's the case... please post about the SPECIFIC issue(s) you're having with the problem.
• what was your approach?
• what did you understand?
• what didn't you understand?
• where did you get stuck?
• did you try any alternate approaches?
etc.

thanks.

__

if you really DID look at this problem and think, "wow, i have NO idea how to do this AT ALL"—then don't study this problem right now!
in that case, you're better off leaving the problem and returning to it later.

...if this is what's happening, then you're basically asking us for the the equivalent of an "answer key".
if we just "walk you through" the entire problem... that's not going to help you develop your problem-solving skills! moreover, you'd be wasting the problem, and GMAT problems are a precious resource.