His brother has 15 rubber bands - 6 rubber bands = <<15-6=9>>9 rubber bands.

They have 15 rubber bands + 9 rubber bands = <<15+9=24>>24 rubber bands together.

# Answer

24
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Harper has 15 rubber bands. His brother has 6 fewer rubber bands than he has. How many rubber bands do they have together?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
24
Harper has 15 rubber bands. His brother has 6 fewer rubber bands than he has. How many rubber bands do they have together?
train