He needs 1.5*40=<<1.5*40=60>>60 pounds of potatoes

So he needs to buy 60/20=<<60/20=3>>3 bags of potatoes

So it cost 3*5=$<<3*5=15>>15

# Answer

15
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
James makes potatoes for a group.  Each person eats 1.5 pounds of potatoes.  He makes potatoes for 40 people.  A 20-pound bag of potatoes costs $5.  How much does it cost?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
15
James makes potatoes for a group.  Each person eats 1.5 pounds of potatoes.  He makes potatoes for 40 people.  A 20-pound bag of potatoes costs $5.  How much does it cost?
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