<|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
 Ten years ago, my older brother was exactly twice the age I was then, my younger sister's age was half of mine, and my youngest brother was the same age as my sister. In fifteen years, the combined age of the four of us will be 110. How old do you think I am now? 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
16
Ten years ago, my older brother was exactly twice the age I was then, my younger sister's age was half of mine, and my youngest brother was the same age as my sister. In fifteen years, the combined age of the four of us will be 110. How old do you think I am now?
test