excel unique value 2 conditions

Win XP SVC Pack3   XP 2007 SVC 2  uniquevalue2conditions.xls

=AVERAGEIFS('3 Months Data'!$I:$I,'3 Months Data'!$M:$M,2,'3 Months Data'!$P:$P,0)
Tells me average charges column I where DOW column M = 2 (Monday) and not a holiday or a special day column P = 0

I want average number of customers on Monday
=SUMIFS('3 Months Data'!$Q:$Q,'3 Months Data'!$M:$M,2,'3 Months Data'!$P:$P,0)
Tells me total numbers of Monday customers Column Q = Cases 1 per line   867
{=SUM(IF(FREQUENCY('3 Months Data'!$B:$B,'3 Months Data'!$B:$B)>0,1))}
Tells me number of unique dates, but not number of unique mondays  88

I was hoping this would tell me number of unique mondays but it shows 0
{=SUM(IF(AND(FREQUENCY('3 Months Data'!$B:$B,'3 Months Data'!$B:$B)>0,FREQUENCY('3 Months Data'!$M:$M,'3 Months Data'!$M:$M)=2),1))  }  I am looking for the number 10

Then I could divide formula one by formula two and get that there are 86.7 average customers on a Monday.  I am editing it and saving with Cntrl+Shift+Enter, but I am an arrray beginner.  This way is most likely the long way, but I can explain it to the boss
UniqueValue2conditions.xls