algebra?- correction

Is the answer C?

Given, wx=y

i) wx^2=y
(wx)x=y
yx=y
INSUFFICIENT as you don'tknow the value of y.

ii) y=4 doesn't give you xy as you don't know what w is. INSUFFICIENT.

Combining both, you have xy=4.

the answer is a
1) is sufficient

Can you please explain how (i) is suficient ?

I would think from (i), we get (wx).x = y, since wx = y, we can substitute wx in the (i) equation, => y.x = y. Without knowing the value of y, I would think we don't know the value of xy. I would think answer is C as well. Even assuming we get a quadratic equationd of xy -y = 0 => y(x-1)= 0. This would mean, x can be 1 and y can take any postive value to satisfy the equation. Or, if y = 0, X can take any value. So I'm not sure how (i) is sufficient.

Appreciate anyone's input.

In my opinion answer cannot be A. When GMAT ask for a value it asks for a specific value, not a variable. Therefore, 'y', the only thing drawn from (i) cannot be the answer. Or am I wrong?

I would go for C as well.

What is the source of this problem 'jopup'?

jopup wrote:If wx = y, what is the value of xy?

1) wx^2=16 (<-made a correction here)

2) y=4


please explain how you got it ( if you got it)

Now we're making sense!

(1) w(x^2) = 16

so:

wxx = 16

or

(wx)x = 16

sub in wx = y, we get

(y)x = 16

or

xy = 16, which is exactly what the question is asking us to solve: sufficient.

(2) y = 4

No info about x, insufficient.

(1) is sufficient alone, (2) isn't: choose (A).