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gbb: Senior | Next Rank: 100 Posts; Posts: 30; Joined: Tue Mar 17, 2009 3:59 pm

by gbb » Sat Mar 28, 2009 3:28 pm

X and Y are both prime numbers. Determine X.

(i) x-y=2
(ii)x^2 - y^2 = 120

answer c

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Source: Beat The GMAT — Data Sufficiency | Sat Mar 28, 2009 3:28 pm

cramya: Legendary Member; Posts: 2467; Joined: Thu Aug 28, 2008 6:14 pmFollowed by: 11 members; Thanked: 331 times

by cramya » Sat Mar 28, 2009 3:36 pm

Stmt I

x=5 y=3

x=7 y=5

INSUFF

Stmt II

x=13 y=7
x=17 y=13

INSUFF

Together

x-y = 2

x^2-y^2 = 120

(x+y) (x-y) = 120

x+y = 60

2 equations 2 variables can solve for one single value for x

SUFF

Choose C

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