Sorry I have miscalculated, I have tested her when I had already picked up some experience.
The formula should be like this:
if the girl has lvl 4 in a skill and serves a lvl 4 guest for that job, without any items, cards or room upgrades, she should satisfy only for 40% (if the skill is at the beginning of the level).
each item that can be used for a specific job gives you +5%
each card that can be used for a specific job gives you +5%
the room upgrade gives you +5%
the skill experience at 0xp gives you +0%, but as soon as you pick up some experience this bonus increases to the maximum of +15% or +20% (I don't remember which one, but you need a level 4 skill with a bit more of 500xp)
so calculating your Kay which has only 5xp at lvl 4, she has +40% as base (the guest is level 4, the skill is level 4), +0% for skill (because she has only 5xp for the skill), +5% for 1 item, +5% for 1 card, +5% for room upgrade = 55%
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