What is the ratio of x to y?

[rockrock]

What is the ratio of x to y?

(1) 5x = 2y

(2) 2y = 7x - 8


I dont understand the explanation for why (2) is insufficient:
(2) INSUFFICIENT: This equation CANNOT be solved for x/y. Any equation in the form of ax = by + c, where a, b, and c are constants does NOT provide a ratio of x to y.

I have already gone through NP and EIVs strategy guide and this rule doesnt seem familiar to me.... What is the rule here and why?

[julien.pitteloud]

Hi, nice to meet you. I'm new here.

I suppose the ratio of x to y has to be independent of x and y :

i) x/y=2/5, ok
ii) x/y=2/7+8/(7y), depends on y

maybe this is the reason.

c ya.

[tim]

There is no rule to memorize here. Just turn that equation to something that has x/y on one side, then look at the other side. Do you have a number? If so, the statement is sufficient; if not, insufficient. See Julien's post for the details..