=SUMPRODUCT(SUBTOTAL(3,OFFSET(L2:L100,ROW(L2:L100)-ROW(L2),0,1)),(L2:L100="Agree")+0)

Bob Phillips wrote:
=SUMPRODUCT(SUBTOTAL(3,OFFSET(L2:L100,ROW(L2:L100)-ROW(L2),0,1)),(L2:L100="A
gree"))



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[1] The SumProduct function should implicitly coerce the truth values to
their Excel numeric equivalents.
[2] The lookup functions should have an optional argument for the return
value, defaulting to #N/A in its absence.