How does Grevious Wounds work with support items?

I know that Grevious Wounds reduces the healing received by 40%. What I don't know is let's say soraka has redemption and mikaels crucible (30% extra heal, total 130%), does grevious wounds cut this by 40% to make her heals worth 90%, or does it cut 40% of the 130% (which is 52) which makes her heals worth 78%??