$$\left. \begin{array} { l } { \frac { f - 32 } { 180 } = \frac { c - 0 } { 10 } } \end{array} \right.$$
$f=18c+32$
$c\in \mathrm{C}$
$f=18c+32$
$c\in \mathrm{R}$
