phanikpk wrote:If x+y is Z, Is y positive?
1) x+z=y
2) y+z=x
When given two equations, one approach is to ADD the two equations.
Statement 1: x+z = y
Adding together x+z = y and x+y = z, we get:
(x+z) + (x+y) = y+z
2x + y + z = y + z
2x = 0
x = 0.
If x=0 and z=1, then x+z=y implies that y=1.
In this case, y is positive.
If x=0 and z=0, then x+z=y implies that y=0.
In this case, y is NOT positive.
INSUFFICIENT.
Statement 2: y+z = x
Adding together y+z = x and x+y = z, we get:
(y+z) + (x+y) = x+z
x + 2y + z = x+z
2y = 0
y = 0.
SUFFICIENT.
The correct answer is
B.
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