Answer
$x=2-\dfrac{\log18}{3}\approx1.58$
Work Step by Step
$10^{6-3x}=18$
Apply $\log$ to both sides of the equation:
$\log10^{6-3x}=\log18$
Take $6-3x$ to multiply in front of its $\log$:
$(6-3x)\log10=\log18$
Since $\log10=1$, this equation becomes:
$6-3x=\log18$
$-3x=\log18-6$
$x=\dfrac{6}{3}-\dfrac{\log18}{3}$
$x=2-\dfrac{\log18}{3}\approx1.58$