gmat prep question

yvonne12 wrote:If x+y are greater than 0, is X=1?

I. x/y =1

II. xy=1

why do we need both if 1(1) can only be 1 and its not a matter of signs, since it is stated along with the question.

Consider I.
x/y=1

=> x=y
x+y is positive will mean both x and y are positive and equal
But That is not sufficient to tell What X is

Consider II.

x=1/y
x+y is positive
=> both x,y are positive and y is the resiprocal of x

again not sufficient to tell what x is

Now if u combine I. and II.

x^2=1 and x is positive
which will give you the value of x as 1
which is sufficient

Agree with C.

why is it C?

even if x=1/3, y=3

1) 1/3 /3 = 1
2) 1/3*3=1

Can anyone please explain....?

IMO C
With both the statements we know that X can only be 1. With X+Y > 0 we know X can only be +1.

dunkin77...Please note that 1/3/3 = 1/9 and not 1.

oops sorry... thanks for correcting me.