If the art piece was bought at $4000, and its price in three years will be three times its buying price, it will be worth 3*$4000 = $12000 in another three years.

The price of the art piece will increase by $12000-$4000 = $<<12000-4000=8000>>8000

# Answer

8000
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Three years ago, Rosie purchased an art piece for $4000. The same art piece will be three times as much in another three years. How much money will the art piece have increased by?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
8000
Three years ago, Rosie purchased an art piece for $4000. The same art piece will be three times as much in another three years. How much money will the art piece have increased by?
train