Remember that most manuals assume paved level and dry. Therefore corrections need to made if these conditons do not apply.
The CAP manual suggests that and extra 15% needs to be added (Factor 1.15) for wet. So take 100ft then multiple by 1.15. This is you "actual" landing distance. However, in the cap manual it states "the landing distance must not exceed 60% of the landing distance available". So multiple again by 1.67 to find out what that available distance is. Now you'll see the number 192 pop into the calculator.
Your actaul landing distance which you have calculated using graphs and wet factor is not allowed to be more than 60% of the available landing distance!!. It does mean it "available to use", it means that there must be some spare runway left when you land in case you hicup or sneeze and balls up the landing. Its for safety.