Damage % Stacking

Can someone tell me how the percentages stack here, if I was hitting a demon and above 50% Health. Are they added together then added on? ie. if X is original damage, 15%+20%+20%=X+55%. Or are the bonuses added one at a time, don't wanna write otu the formula but it would be more than the first example.

Just curious as to how much more damage i'm actually doing.

~Thanks

Don't forget Lightbringer. That's an additional 40% at max rank, for a grand total of +95% increased damage. I don't recall whether the damage bonus is additive(+55%), or multiplicative(+66%).

It is multiplicative as i suspected and confirmed on Wiki

it's 100% x 1,15 x 1,20 x 1,20, which nets in 165,6% of the original damage.

So if I interpret that correctly if I was Holy Lightbringer, i'd do 231.84% more damage. Rounded to 232%, so i'd do over double damage against a demonic servant of abbadon?

cut off, not rounded. so 231 dmg