help--"there are twice as many X as Y"

How to understand it? Is there any link regarding this topic or the similar topic. Thank you very much. I will take the GMAT soon. Hurry,,,,,

Y是X的2背。Y＝2X。

应该是Y＝2X;

如果x=2y，要表达成there are as many X  twice as Y，记得SC部分看到过这样一个例句的。

Of the 60 animals on a certain farm, 2/3 are either pigs or cows. How many of the animals are cows?

(1)    The farm has more than twice as many cows as it has pigs.

(2)    The farm has more than 12 pigs

这道题目中就是这样的表达，而答案是cows＝28，pig= 12

这道题目中就是这样的表达，而答案是cows＝28，pig= 12

if the farm has more than 12 pigs, then pig can not be 12, since 12 is not bigger than 12

I remembered I did this problem, the answer should be cows = 27 and pigs = 13, for 1) cows = 27 > 26 = 2 * 13 = 2 * pigs, where the farm has more than twice as many pigs as it has cows(I'm pretty sure u have the problem wrong), and 2) pigs = 13 > 12, where the farm has more than 12 pigs

I just noticed that I forgot to mention about the orginal question, here it is:

twice as many x as y: "twice as many x" and "as y" are the two things that are being compared, so in a way, "2x" and "y" are the same;

as for "more than twice as many x as y", if we use "more than" that means something is more than something else, there is not equality here, so "more than twice as many x" and "as y" are once again the two things that are being compared, so "something more than 2x" => ">2x" and "y" are the same, thus y > 2x