Question about attributes

App_Maker

Heres what im trying to do im making a rpg game and have the player hp attribute currently set to 100 then when i add armor the issue is that when you go from having armor =1 to then changing armor to =2 it adds the 20hp + 50hp to show 70hp and not 50hp for only having armor 2 equip. I only want it to do one or the other. Also i want to include different equipment like a weapon lets say to also add to player hp. So only one weapon and one piece of armors attributes will show and if its not equip it will be 0.
Rule
When armor = 1
Change attribute Player Hp to Player Hp+20
Rule
When armor = 2
Change attribute Player Hp to Player Hp+50