sum unique entries only

[Jo]

I need help with a formula. I have the following formula giving me the no of
unique positions that are ines 4

=SUM(--(FREQUENCY(IF((SUBTOTAL(3,OFFSET($D$1,ROW($D$2:$D$671)-ROW($D$1),,1)))*($E$2:$E$671="INES"),$D$2:$D$671,""),IF((SUBTOTAL(3,OFFSET($D$1,ROW($D$2:$D$671)-ROW($D$1),,1)))*($E$2:$E$671="INES"),$D$2:$D$671,""))>0))

col d col e col f
pos no cat fte
10 ines .5
10 ines .5
15 ines 1
20 ines 1
25 ines 1
25 ines 1

I now need it to tell me that i have fte of 3.5 so find the unique value
column d that is ines and multiple it by column f

Thanks for helping