The value you seek has 4 subtracted, the log taken, and the result multiplied by 3. To find that value, divide by 3, take the anti-log, then add 4. (Undo the steps that were done to the variable.)
3Ln[x-4] = 6
Ln[x-4] = 2 (divide by 3)
x - 4 = e^2 (take the anti-log)
x = 4 + e^2 (add 4)
x ≈ 11.389 (compute the result)
3Ln[x-4] = 6
Ln[x-4] = 2 (divide by 3)
x - 4 = e^2 (take the anti-log)
x = 4 + e^2 (add 4)
x ≈ 11.389 (compute the result)