The second warehouse has 400/2 = <<400/2=200>>200 boxes.

Collectively, there are 400+200 = <<400+200=600>>600 boxes in the first and second warehouse.

# Answer

600
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
There are two warehouses. The first warehouse has twice as many boxes as the second warehouse. If the first warehouse has 400 boxes, how many boxes are there in both warehouses combined?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
600
There are two warehouses. The first warehouse has twice as many boxes as the second warehouse. If the first warehouse has 400 boxes, how many boxes are there in both warehouses combined?
train