I'd have thought that if you were aware that you could contribute camels to a building project, then it'd be pretty obviouswhat would be required, even though the city is on it's own. The clever thing here is to ensure that you have the boat in the city at the start of the turn, and the camels asleep. This way you can move one square out of the city, and then wake the camels to reenter it. If you move onto a boat then it costs all of your movement points so you'd use two turns moving the camels out onto a waiting boat and then back into the wonder.
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