Yep very simple, let me simplify it for you.Lol you guys need to pay attention in Maths class.
Very simple
New weapon speed = Old Weapon speed x [1-(Haste %/100)]
Example
Weapon speed = 2000
Using 30% haste gloves
New weapon speed = 2000 x [1-(30/100)] = 2000 x [1-0.3) = 2000 x 0.7 = 1400
Yoi shouldnt really need an equation but im guessing you guys cant work out %s in your head.
Example
Weapon speed = 2000
Using 30% haste gloves
2000 x 0.30 = 600
2000 - 600 = 1400
Or even simpler, use a calculator and just type in 2000-30% and it gives you it right there.