Kidzone.ws Word Problem

Mr. Brown is getting his boat ready for fishing now that the ice is melting.  His boat holds 13 gallons of gasoline in total.  He has 8 gallons of gasoline left from last year.  How many more gallons of gasoline does Mr. Brown need to buy to fill his boat?

Write the math equation: ______________________

How many gallons must Mr. Brown buy? _______

 
Show your work!