How do you get 2-for-1 at Ports/Warehouses?

[Wolverine@MSU]

I noticed in several maps that warehouses can supply 2 of something in exchange for one of something else. How id this done. I don't see any options on the Port/Warehouse setups that allow this, only the maximum number of all products.

[Gwizz]

First set a port to only supply 2 of something then change/add a demand cargo that produces those first 2 cargos.

[EPH]

I always put a port or warehouse on the map so I can instantly check the values. Then set both supply and demand and check the port or warehouse for confirmation. The port/warehouse can then be deleted if desired.

Be advised that supply demand ratios of x for 1 are possible but other ratios (such as 3 for 2) are not.

[Wolverine@MSU]

First set a port to only supply 2 of something then change/add a demand cargo that produces those first 2 cargos.

Do you have to do a "save" or exit out of the warehouse set up screen before adding the new demand cargo or can you just set up to supply 2 of something (wool, for instance) and then change it to exchange say grain for wool.

[wsherrick]

You can change the demand/supply number in the editor. It's in the upper right hand corner of the ports/warehouse section. Just go up there and click on it. I don't know how to change the demand/supply proportion though. Another good question to ask, which I never thought of until now-does the ratio have to do with the price or value of a product versus another, for example; is cotton worth less than furniture or cars, so it would take say 2 cottons for one car?

[EPH]

As far as I know the exchange isn't made by price but by quantity alone, but it only works as demanding one unit and supplying one or more.