10^log(x+3) = 10²
x + 3 = 100
x = 97

e^log(x+3) = e²

ln(3x) = 4
e^ln(3x) = e⁴

$\text{ln}\frac{x+4}{x}=2$

$e^{\text{ln}\frac{x+4}{x}}=e^{2}$

$\frac{x+4}{x}=e^{2}$

x + 4 = xe²
x − xe² = −4
x(1 − e²) = −4

$x=\frac{-4}{1-e^{2}}\Rightarrow \frac{4}{e^{2}-1}$