Formula to Sum monthly Total for any Overtime worked and deduct Absent days

Hello All, I have an excel sheet for daily hours worked shown as 8, OT will be 12 (i.e. 8+4) and any absence would be marked as A. I have a column where I use the regular sum function to add up all the days worked which works fine. My problem is a formula which should take the extra 4 hours from any cell from the value of 12 on any day within the range and plus if there is an A in the Cell then it should deduct 8 for each A in the range.