<|im_start|>system
You are a helpful assistant. You first think about the reasoning process in the mind and then provide the user with the answer. You should try to truely solve the question by yourself without cheating.  <|im_end|>
<|im_start|>user
 A merchant reduces the purchase price by 8% while keeping the selling price unchanged. As a result, the profit margin (based on purchase price) increases from x% to (x+10)%. Calculate the initial profit margin x. Express your answer as a percentage. Show your work in <think> </think> tags. And return the final answer in <answer> </answer> tags.<|im_end|>
<|im_start|>assistant
Let me solve this step by step.
<think>
user
15
A merchant reduces the purchase price by 8% while keeping the selling price unchanged. As a result, the profit margin (based on purchase price) increases from x% to (x+10)%. Calculate the initial profit margin x. Express your answer as a percentage.
test