Formula for salary and equity

There are a lot of resources scattered all over Internet about how salary or equity should be determined whenever you either found a start or join one. The thing is that there's no clear answer. It's more of the heuristic at start.

Buffer has released the way the calculate salary and equity including the spreadsheet with all calculations.

(Role x Experience + Choice) x Loyalty = Salary

Role x Choice / Risk Layer + Seniority = Equity