The Sheikh and the Camels

A Sheikh dies, leaving behind three sons, 17 camels, and the following order:

  1. The oldest son shall inherit one in two camels.
  2. The middle son shall inherit one in three camels. 
  3. The youngest son shall inherit one in nine camels. 

Now the three sons do not know what to do. They ask an old friend of the family for advice, and he finds a solution.

What did the friend propose?

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The friend lended them one camel to make the camels 18. The first son took 9 camels, the second son took 6 camels, the third son took 2 camels. Then the friend took back his camel.