Trade agreements

[Tanus]

Just to throw the math in here because people hate it so much

As an example.
If your treaty with empire A is at 17%, and you are making 100,000 minerals from colonies and 10,000 minerals from trade with A.

empire A has total income (disregarding trade/remote mining) of:
10,000 * (100/17) = ~59,000

you are giving empire A in trade:
100,000 * (17/100) = ~17,000

hope that helps