<|im_start|>system
You are a helpful assistant. You first thinks about the reasoning process in the mind and then provides the user with the answer.<|im_end|>
<|im_start|>user
Using the numbers [9, 9, 9, 9], create an equation that equals 81. You can use basic arithmetic operations (+, -, *, /) and each number can only be used once. Show your work in <think> </think> tags. Also, provide the solution in a <answer> tag, for example, <answer> (9 + 9) * (9 - 9 / 9) = 81 </answer>. <|im_end|>
<|im_start|>assistant
Let me solve this step by step.
<think>