Sex is related to Boy. Boy is related to Seed. Seed is related to Growth. 
Flat is related to Spare. Favor is a type of Spare. Favor is the opposite of Balance. 
Sex <--RelatedTo--> Boy <--RelatedTo--> Seed <--RelatedTo--> Growth 
Flat <--RelatedTo--> Spare <--IsA-- Favor <--Antonym--> Balance 