Really cool! Unfortunately Numbers doesn't support more complicated SUMPRODUCT formulas...
=(income-INDEX(bracket_min,match(income,bracket_min,1)))*
INDEX(bracket_tax,match(income,bracket_min,1))+
INDEX(bracket_base_tax,match(income,bracket_min,1))It's simpler, and Lotus 1-2-3 doesn't have MATCH! :-)
I think something like this would work...
(income-@VLOOKUP(income,table,1))*@VLOOKUP(income,table,3)+@VLOOKUP(income,table,5)