$4+7=3+8$ 
The last five digits of Zoe\textquotesingle s phone number are $3,4,8,5,7.$ If these $5$ digits are filled in the square~$$\huge\square+\square =\square +\square $$, which number is not used?~(adapted from $$2017$$ Math kangaroo Problems, Level $$1-2$$, Question \#$$8$$) 
Options:
  - $$3$$ 
  - $$4$$ 
  - $$5$$ 
  - $$7$$ 
  - $$8$$ 