Fire is the opposite of Air. Air is a synonym of Appearance. 
Wealth is the opposite of Debt. Debt is related to Financial. Financial is related to Gain. Round is a type of Gain. 
Fire <--Antonym--> Air <--Synonym--> Appearance 
Wealth <--Antonym--> Debt <--RelatedTo--> Financial <--RelatedTo--> Gain <--IsA-- Round 