Math is related to Calculation. Calculation is related to Divide. Divide is a synonym of Fraction. 
Rent is a type of Contract. Contract is a synonym of Diminish. Diminish is a synonym of Fade. Fade is a synonym of Melt. 
Math <--RelatedTo--> Calculation <--RelatedTo--> Divide <--Synonym--> Fraction 
Rent --IsA--> Contract <--Synonym--> Diminish <--Synonym--> Fade <--Synonym--> Melt 