Answer
Yes, it is a solution.
Work Step by Step
$3x=-\frac{5}{6}$
$3(-\frac {5}{18})\overset?=-\frac{5}{6}$
$(-\frac {15}{18})\overset?=-\frac{5}{6}$
$(-\frac {15\div3}{18\div3})\overset?=-\frac{5}{6}$
$(-\frac {5}{6})\overset?=-\frac{5}{6}\checkmark$