<|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 is older than b by 5 years. In a certain number of years, thrice a's age shall be equal to 4 times that of b. Their present ages are 13. How many years from now will this happen? 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
11
a is older than b by 5 years. In a certain number of years, thrice a's age shall be equal to 4 times that of b. Their present ages are 13. How many years from now will this happen?
test