Answer
Since $x \ne -5$, then $x = 2$
Work Step by Step
$\log x + \log (x+3) = \log 10$
$\log [x(x+3)] = \log 10$
$\log (x^{2} + 3x) = \log 10$
$x^{2} + 3x = 10$
$x^{2} + 3x - 10 = 0$
$(x+5)(x-2) = 0$
$x = -5, 2$
Since $x \ne -5$, then $x = 2$