$$\log\ c-4=8x+18.$$
$c=10000000000000000000000\times 100000000^{x}$
$Im(\ln(100000000^{x}))-8\ln(10)Im(x)=0$
$x=\frac{\log(c)-22}{8}$
$c\neq 0$
$c=10000000000000000000000\times 100000000^{x}$
$x=\frac{\log(c)-22}{8}$
$c>0$