I have to get food as high while water is low.
Ok, I have enough food, but I need firewood to keep warm and water because one of my containers leaked.  So, why don't you take all the food and I get everything else.
Sure, I'll agree with it!
🙂 Ok.
I can give you 1 thing of water and 2 things of firewood
Hmmm. So you will end up with 1 firewood, 3 food, and 2 water?  I think I need 1 more water and 1 more food. 
I'll give you another water and food
I think we have a deal.  To confirm, YOU get 1 firewood, 2 food, and 1 water?  If yes, please confirm.  I think this sounds fair.
Yep, it's correct
Ok.  I will submit the final offer.  I appreciate your offer.