Schreibe das einfach mal um:$$\log_{a}{b}=\frac{ln(b)}{ln(a)}$$$$\frac{ln(16)}{ln(3)}=\frac{ln(256)}{ln(x)} \quad |\cdot ln(x)$$$$\frac{ln(16)}{ln(3)}\cdot ln(x)=ln(256) \quad |:\frac{ln(16)}{ln(3)}$$$$ ln(x)=ln(256) :\frac{ln(16)}{ln(3)}$$$$x=e^{\frac{ln(256)}{\left(\frac{ln(16)}{ln(3)}\right)}}$$$$x=9$$