If $\displaystyle \left(\frac{3}{4}\right)^x=\frac{81}{256}$, what must $x$ be?
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
If $\displaystyle \left(\frac{3}{4}\right)^x=\frac{81}{256}$, what must $x$ be?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
4
If $\displaystyle \left(\frac{3}{4}\right)^x=\frac{81}{256}$, what must $x$ be?
train