Mary went to the stationery store and she bought three pencils, a notebook, and a stationery box. A pencil costs $1$ dollar, a notebook costs $2$ dollars, a pencil case costs $3$ dollars, and Mary has a $1$ dollar discount coupon. How much did Mary spend in the end?~(adapted from $$2005$$ Math kangaroo Problems, Level $$1-2$$, Question \#$$6$$) 
Overseas Competition->Knowledge Point->Calculation Modules->Whole Numbers->Whole Numbers Addition and Subtraction ->Addition and Subtraction of Whole Numbers->Questions Involving Addition and Subtraction
Three pencils are three dollars. Notebook is two dollars. A three dollar pencil case and a one dollar free at last. So the last answer is $3+2+3-1=7$ 