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independent
- Junior | Next Rank: 30 Posts
- Posts: 17
- Joined: Sat Mar 17, 2012 2:27 pm
- GMAT Score:600
Hi,independent wrote:
Can someone please explain why is statement 2 sufficient?
OA: D
Statement(2):
Given:
-2x > 3y -- (1)
and
2x + 5y = 20 -- (2)
Let me show you a very useful method in such problems.
Substituting y = (20 - 2x)/5 from (2) in (1):
-2x > 3*(20 - 2x)/5
We have an inequality now with only the desired variable 'x'. Solving further:
-10x > 60 -6x
-4x > 60
Dividing both sides by -4 and reversing the sign of the inequality,
x < -15
which shows that x is definitely negative.
SUFFICIENT
It takes a little bit of practice to combine an equation and an inequality as shown above. Notice that I substituted 'y', and not 'x', into the inequality because I wanted the final inequality only in terms of the variable about which the question has been asked.
