Assuming that A2 contains the start date, and B2 contains the end date,
try the following...
To count the number of Mondays...
=SUMPRODUCT(--(WEEKDAY(ROW(INDIRECT(A2&":"&B2)),2)=1))
To count the number of Mondays, Wednesdays, and Fridays...
=SUMPRODUCT(--ISNUMBER(MATCH(WEEKDAY(ROW(INDIRECT(A2&":"&B2)),2),{1,3,5},
0)))
Change the return type for the WEEDAY functions accordingly...
Monday = 1
Tuesday = 2
Wednesday = 3
Thursday = 4
Friday = 5
Saturday = 6
Sunday = 7
Hope this helps!
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