mrsmarthi wrote:

peraspera wrote:

Let me take a stab.

1. 2x-2y-=1

2x = 1 + 2y

x = (1+2y)/2=0.5 +y

not suff.

2. x/y>1

multiply by y => x>y

not suff.

combining them both, it's sufficient:

x=0.5+y and x>y => 0.5+y>y

this makes sense only if y<0

So, it's C.

X/y > 1 ==> x > y This is is not true in Ineqalities. You cannot multiple denominator value on both sides.

Here is an ex Let x = -3 and y = -2 ==? -3 / -2 > 1. This does not mean that -3 > -2. So your approach on Second clue is incorrect. I think you need to revisit the logic.

Thank you so much, I can't believe I still make this stupid mistake.

You are correct, I cannot do that.

Here's the (2) and the solution, then:

2. x/y>1, so then x and y have the same signs, either -, or +.

Furthermore, x>y if their signs are positive and x<y if their signs are negative.

insuff.

Let's combine (1) and (2).

if x and y are negative, then -x=0.5+(-y) or -x+y=0.5 - this can never be possible, because from (2) we know that x<y if their signs are negative. E.g. if x=-3, and y=-2, then -3+2 cannot equal 0.5.

if x and y are positive, then x=0.5+y or x-y=0.5 - this is possible, because from (2) we know that x>y if their signs are positive.

So, C is sufficient, x and y are both positive.

I hope it makes sense.