Data Sufficiency (DS) | Re: If wx>0, xy>0, and yz

Because \(z^2\) is always positive, therefore the question is really asking if w<0. And wx>0 so if we know the sign of x we can answer the question.

1- z is positive => y negative => x is negative, we know the sign, SUFF
2- x<0, we know the sign, SUFF

Answer is D.

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