Depict a picture of a pastoral scene with various herds of cows, illustrating the given mathematical problem. On one side, show 15 cows grouped together, symbolizing Fred's herd while on the other side, show a herd of cows that is visually twice as large to symbolize John's larger herd.

Fred has 15 cows

John has twice as many cows as Fred had
when Fred had as many cows as John has now
how many cows has John?

The logic is circular; thus, there is no answer. It is a literary version of an optical illusion such as the one where there is a set of descending stairs and the end of the stairs returns to the beginning.

Here is a slight rewording: Fred has as many cows as John has now, but john has twice as many cows. I first heard this riddle in a rerun of the 1957 TV show "The Rifleman", episode 17 (yesterday). The riddle is worse when all you can do is listen and not read it. So, I looked it up to ensure that I was understanding it correctly and here I am. 60 is NOT the answer. This is a dog chasing its own tail.

It takes about 15 seconds to realize there is no way to arrive at the answer. 15 cows, has nothing to do with the rest of the quest. Whoever wrote Mark McCain's text book should be fired ;).

60

John has no cows

A = cows Fred had before
B = cows Fred has now
J = cows John has now

B = 15
J = 2A
A = J

A = 2A --> A = 0
J = 2 * 0 = 0

60

Explain how you get 60. It seems to me as though there's insufficient information to solve this problem.

In order for John to have twice as many cows as Fred had when Fred had as many cows as John has now John has zero cows. Two times zero is zero.

I saw that “Rifleman” episode yesterday.

I agree that there is no conclusive answer.

Does anyone remember this riddle from that show:

“Where was the man when he jumped off the bridge”?

“In the air” - “no, that was after he jumped”.

“On the bridge” - no, that was before he jumped.

Ah, my wasted youth!

Moot

The logic is circular; thus, there is no answer. It is a literary version of an optical illusion such as the one where there is a set of descending stairs and the end of the stairs returns to the beginning.

Here is a slight rewording: Fred has as many cows as John has now, but john has twice as many cows. I first heard this riddle in a rerun of the 1957 TV show "The Rifleman", episode 17 (yesterday). The riddle is worse when all you can do is listen and not read it. So, I looked it up to ensure that I was understanding it correctly and here I am. 60 is NOT the answer. This is a dog chasing its own tail.