You do the math.., Equipment costs question Options

[Brazila]

Okay, this has been brought up in our group and so I was wondering what everyone else does for this. The question is simply how do you do the math in your games. For instance a kid stealth leg costs 100,000, now let's say you make it alpha grade, and your a troll, what is your total cost? Would it be:
100,000*(200%+25%=225%)=225,000
or would it be :
(100,000*200%)*125%=250,000
Do you add the % multipliers together like 3rd edition D&D or do you apply one get a new base then apply the next? When you get enough multipliers this can make a huge difference.

I mean if your base gear is 100,000 then times 2 for alpha, then say +25% for being a troll, then say it's one of the pieces that is reduced in cost for having multiple cyberlimbs so you get 30% off. This could be either 175,000 or 195,000 depending on the math.