Stacking of buffs

So, since I get rather curious, I started asking--How do Self-Care and Resilience stack? Here are their numbers:
"Unlocks the ability to heal yourself without a Med-Kit IconItems firstAidKit.png at 50 % the normal Healing speed."

Meanwhile, Resilience states: Grants 3/6/9 % additional speed when repairing, sabotaging, healing, unhooking, vaulting, cleansing, opening Exit Gates and searching Chests while Injured IconHelp injured.png.

So, with those together, depending on stacking, we get 54.5% the normal heal speed... Or 59% the normal speed.
Which is it? Does anyone know?