The grill burned 3 * 60 = <<3*60=180>>180 coals.

It takes 20 minutes to burn 15 coals, so the grill ran for 180 / 15 * 20 = <<180/15*20=240>>240 minutes.

# Answer

240
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
A charcoal grill burns fifteen coals to ash every twenty minutes of grilling. The grill ran for long enough to burn three bags of coals. Each bag of coal contains 60 coals. How long did the grill run?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
240
A charcoal grill burns fifteen coals to ash every twenty minutes of grilling. The grill ran for long enough to burn three bags of coals. Each bag of coal contains 60 coals. How long did the grill run?
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