<|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 vessel with a capacity of 6 liters contains 4 liters of a 70% sulfuric acid solution. Another vessel of the same capacity contains 3 liters of a 90% sulfuric acid solution. Some amount of the solution is transferred from the second vessel to the first one so that the first vessel ends up with an \( r\% \) sulfuric acid solution. Find the largest integer value of \( r \) for which the problem has a solution. 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
76
A vessel with a capacity of 6 liters contains 4 liters of a 70% sulfuric acid solution. Another vessel of the same capacity contains 3 liters of a 90% sulfuric acid solution. Some amount of the solution is transferred from the second vessel to the first one so that the first vessel ends up with an \( r\% \) sulfuric acid solution. Find the largest integer value of \( r \) for which the problem has a solution.
test