Total square footage is 16*10=<<16*10=160>>160 square feet

There are 3+3=<<3+3=6>>6 rooms

6-1=<<6-1=5>>5 of them are the same size

If x is the size of the normal room then the square footage of all rooms is 5x+3x=8x

So each room is 160/8=<<160/8=20>>20 square feet

So the living room is 20*3=<<20*3=60>>60 square feet

# Answer

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<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Mark builds an apartment that is 16 by 10 feet.  There are 6 rooms in total.  All the rooms are the same size except the living room which is as big as 3 other rooms.  How big is the living room?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
60
Mark builds an apartment that is 16 by 10 feet.  There are 6 rooms in total.  All the rooms are the same size except the living room which is as big as 3 other rooms.  How big is the living room?
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