Answer
$x =\dfrac{\ln{10}}{3}$
Work Step by Step
Take the natural logarithm of both sides to obtain:
$\ln{e^{3x}} = \ln{10}$
RECALL:
$\ln{e^a} = a$
Use the rule above to obtain:
$3x=\ln{10}$
Divide by 3 on both sides of the equation to obtain:
$x =\dfrac{\ln{10}}{3}$