<|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 [-10, -7, -3, -1], find an equation that equals 70. Each number can only be used once for basic arithmetic operations (add, subtract, multiply, divide). Show your work in <think> </think> tags. Return your final equation and answer in <answer> </answer> tags, for example <answer> (-10 + 7) * (-3 - 1) = 70 </answer>.<|im_end|>
<|im_start|>assistant
Let me solve this step by step.
<think>