Answer
$x = 3.010$
Work Step by Step
$\log (x-3) = -2$
$\log_{10} (x-3) = -2$
$10^{-2} = x - 3$
$0.01 = x - 3$
$0.01 + 3 = x$
$x = 3.010$
Check:
$\log_{10} (3.010-3) \overset{?}{=} -2$
$\log_{10} (0.01) \overset{?}{=} -2$
$\log_{10} (10^{-2}) \overset{?}{=} -2$
$-2\log_{10} (10) \overset{?}{=} -2$
$-2(1) \overset{?}{=} -2$
$-2 = -2$