how many hours did they work per week out of 168?
A couple of ways it can be figured. The article is unclear.
Typically it is a base week of five eight hour days at straight time (normal hourly rate).
Between eight and twelve hours are time and a half (you accrue 0.5 hours of premium time each hour)
After twelve hours is double time (you accrue 1 hour of premium time each hour)
Saturday is time and a half, Sunday and holidays are double time.
So you have hours worked plus the premium time; equals hours on the check. Or it can be simply hours worked.