Solve for $a$: $\dfrac{8^{-1}}{4^{-1}}-a^{-1}=1$.
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Solve for $a$: $\dfrac{8^{-1}}{4^{-1}}-a^{-1}=1$.
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
-2
Solve for $a$: $\dfrac{8^{-1}}{4^{-1}}-a^{-1}=1$.
train