Have tried a lot but failed! I am making photography of Real Estate and charge per square feet. Fixed price is $35 Variable are: 75 cents per sqf up to 2,500 37,5 cents from 2,501 and up. Houses are from 900 to 12,000 sqf. Tried to do at least twelve different formulas but can not get it right! End up with negative when lower sqf than 2,500. Anyone knows here that knows where I can get help? At least I have tried but not sure how I should create my formula!!!