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teejaycrown
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(1) 2x - 2y = 1 implies x - y = 1/2 or x = y + (1/2)teejaycrown wrote:Are x and y both positive
1. 2x - 2y = 1
2. x/y > 1
If y = 4, then x = 4 + (1/2) = 5/2 = positive
If y = -3/2, then x = (-3/2) + (1/2) = -1 = negative
No definite answer; NOT sufficient.
(2) x/y > 1 implies x and y could be both positive or both negative.
No definite answer; NOT sufficient.
Combining (1) and (2), x = y + (1/2) and x/y > 1
x/y > 1 implies (x/y) - 1 > 0 or (x - y)/y > 0
Now substitute x = y + (1/2) in the above inequality:
{y + (1/2) - y}/y > 0
1/(2y) > 0
1/y > 0 implies y > 0 or y is positive.
Since x = y + (1/2), so x will also be positive; SUFFICIENT.
The correct answer is C.
