Multiple If Statement

I am having problems with this and I don't usually have problems with if
statements.

I want to sum that will say -

if b8 ="Sat" then return i7
if b8 = "Sun" then return i7
if b8 <> "Sat" or "Sun" and j8 >0 then i7+j8
if b8 <> "Sat" or "Sun" and j8 = 0 then 0

Many thanks for any help.