Extracting Poison and Alchemy

When extracting poisons from plants, does the target number reduce by 4 for each additional slot of Alchemy you have?

For example, the normal target number is 14+. If I have 3 slots of Alchemy, would that reduce to 6+?

I think it does, but I just want to be sure.

In general, an additional rank in the proficiency reduces proficiency rolls required by 4.

Perfect. Thanks for the hasted response.