Will you please give me 2 packages of food?
If I give you 2 packages of food, can you give me 2 packages of Firewood ? 
That will be tricky, let me give you 2 packages of water and 1 package of firewood.
I have a higher need for Firewood. I can give you 2 packages of food and 1 package of water for 2 packages of firewood 
Oay seems like we have a deal.
Ok, great! It was a pleasure working with you! 
Pleasure is all mine🙂
So, to be clear. You agree to get 1 package of fire Wood, 2 Packages of water, and 2 Packages of food? 
Yeah, that's right.
Ok, great! I am glad we are both in consensus on that.