Answer
$1~N/C = 1~V/m$
Work Step by Step
We can express $1~N/C$ in SI units:
$1~N/C = 1~\frac{kg~m}{C~s^2}$
We can express $1~V/m$ in SI units:
$1~V/m = 1~\frac{J}{C~m} = 1~\frac{kg~m^2}{C~m~s^2} = 1~\frac{kg~m}{C~s^2}$
We can see that $1~N/C = 1~V/m$
