Concentrated Effect and Increase area of effect

I am wondering which one applies first? Is there an increase of 18% of the area of effect and then a reduction of 30%. Or is it subtracted then added? Being able to combine the two, if they nullify each other's effect would give a free 50% damage boost.

"Increased" and "reduced" are two sides of the same coin, and apply additively except that one is positive and the other is negative. So, if you have Amplify's +12% Increased Area of Effect Radius and Concentrated Effect's -30% Reduced Area of Effect Radius, then your total is -20% Area of Effect Radius no matter which occurs first.

They interact additively. If you have a Concentrated Effect gem (30% reduced) and a level 1 Increased Area of Effect gem (14% increased), you have 16% reduced AoE.

Thanks guys :)