Formula for adding a percentage from one cell and adding the total of 2 others

=sum(k:K)*0.4+sum(n:o) or do you mean something else?

if its the whole column or a range say
=sum(k1:K10)*0.4+sum(n1:O10)
then no
if its only each row you want to do
k1*0.4+sum(n1:O1)

you can use % instead of decimal eg

=sum(k1:K10)*40%+sum(n1:O10)

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