<|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, 30, 15, 20], create an equation that equals 57. You can use the basic arithmetic operations (+, -, *, /) and each number can only be used once. Display your steps in the <think> </think> section. Provide your final answer in <answer> </answer> tags, for example <answer> (20 - 10) * 3 = 30</answer> and check if it meets the target.<|im_end|>
<|im_start|>assistant
Let me solve this step by step.
<think>