My attempt doesn't work:

If Columns("B:B") = "A" And Columns("N:N") = "manual Calc" Then
Columns("O:O") = "0"

I need it to see if column B has value "A" in it with a matching row of
column N with value "manual Calc" and if true then set the same rows column O
to a value of "0".
Thanks in advance for your expert advice!