The total time we spent going to school is 15 minutes + 6 minutes = <<15+6=21>>21 minutes.

We have 30 minutes - 21 minutes = <<30-21=9>>9 minutes left not to be late.

# Answer

9
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
My brother and I have thirty minutes to go to school, without being late. It takes us 15 minutes to arrive at the school gate, and another 6 minutes to get to the school building. How much time do we have to get to our room, without being late?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
9
My brother and I have thirty minutes to go to school, without being late. It takes us 15 minutes to arrive at the school gate, and another 6 minutes to get to the school building. How much time do we have to get to our room, without being late?
train