Find the positive base $b$ in which the equation $5 \cdot 25_b = 137_b$ is valid.
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Find the positive base $b$ in which the equation $5 \cdot 25_b = 137_b$ is valid.
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
9
Find the positive base $b$ in which the equation $5 \cdot 25_b = 137_b$ is valid.
train