Would a counterexample be enough? Try x=4, y=7.

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- July 19th 2008, 11:38 AM #1

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## Mod 15

Q: If 5x=5y (mod 15), then could someone please explain to me why it's NOT true to say that x=y (mod 15) but it IS true to say x=y (mod 3)? Just a little confused as to why I can't divide both sides by 5 in the first instance to give x=y (mod 15) and yet I can for x=y (mod 3).

- July 19th 2008, 11:49 AM #2

- July 20th 2008, 01:09 AM #3