Suggested Answer
You have two equations:1st: [tex]1J=1N*1m[/tex]and2nd: [tex]1V=\frac{1J}{1C}[/tex]from the second equation you can extract Joule:[tex]1J=1V*1C[/tex]you compare right side of the equation above to the right side of the 1s equation:[tex]1V*1C=1N*1m[/tex]then you devide both sides by 1C and by 1m and you get:[tex]\frac{1V}{1m}=\frac{1N}{1C}[/tex]