<|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 [87, 95, 72, 28], devise a mathematical operation that sums up to 109. You are free to use basic arithmetic operations (+, -, *, /) and the number can only be used once for each operation or expression. Present your reasoning within <think> </think> tags. And return the solution in your answer in <answer> </answer> tag, for instance, <answer> (some operation) = 109 </answer>.<|im_end|>
<|im_start|>assistant
Let me solve this step by step.
<think>