Fast is the opposite of Weak. Weak is a synonym of Delicate. Delicate is related to Butterfly. Butterfly is related to Hand. 
Spend is the opposite of Tax. Tax is the opposite of Money. 
Fast <--Antonym--> Weak <--Synonym--> Delicate <--RelatedTo--> Butterfly <--RelatedTo--> Hand 
Spend <--Antonym--> Tax <--Antonym--> Money 