<|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 [4, 25, 81, 7], create an equation that equals 150. You need to use each number only once and the equation must be constructed using basic arithmetic operations (+: addition, -: subtraction, *: multiplication, /: division). Show your work in <think> </think> tags. Return the final equation and answer in <answer> </answer> tags, for example <answer> (3 + 4) * 25 = 150 </answer>.<|im_end|>
<|im_start|>assistant
Let me solve this step by step.
<think>