Answer
$x\approx 3.0589$
Work Step by Step
Use a graphing utility to graph the functions $y=6^{3x+1}$(refer to the black graph below) and $y=215$ (refer to the red graph).
Use the graphing utility's table of values function (refer to the attached image below for the table).
Thus, the solution rounded to the nearest ten-thousdandths is $x\approx 3.0589$.
