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This question already has an answer here:

I want to prove that if $5\mid(a+11)$ and $5\mid(16-b)$ then $5\mid(a+b)$

Can you help me?

Thanks in advance PS. It's urgent!

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marked as duplicate by amWhy, Douglas S. Stones, Math Gems, Jasper Loy, Mike Apr 2 '13 at 18:17

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

Exact duplicate of said question from 14 hours ago. – Math Gems Apr 2 '13 at 18:14
@amWhy Yes, the point of my comment was to say more than the the terse automatic message, so that voters have further info on which to base their decision. – Math Gems Apr 2 '13 at 18:18

Hint: $$a + b = (a + 11) - (16 - b) + 5$$

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That seems like a bit more than a hint :) – Thomas Andrews Apr 2 '13 at 18:07

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