For the walls of the house he would use w nails in all to secure large planks of wood. If each plank needs x pieces of nails to be secured and an additional y nails were used. How many planks does John need for the house wall?
There are 11 walls in the house. 
Each wall needs 3 pieces of nails to be secured. 
An additional 8 nails were used. 

Therefore, John needs 33 planks for the house wall.