<|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
You are a 15-year-old player preparing to play the Countdown Game. You have drawn the following numbers: [21, 85, 64, 10]. The target number you need to reach is 55. Using basic arithmetic operations (+, -, *, /) and each number only once, create an equation that equals 55. Show your work in <think> </think> tags and provide the final equation and answer in <answer> </answer> tags. For example, <answer> 85 / 10 + 64 = 55 </answer> would be an invalid solution because the first number used was 10, which has already been used. Good luck!<|im_end|>
<|im_start|>assistant
Let me solve this step by step.
<think>