<human>:  If a vehicle is driven 12 miles on Monday, 18 miles on Tuesday, and 21 miles on Wednesday. What is the average distance traveled per day?
<bot>: How many miles are covered from Monday to Wednesday? ** The total distance covered from Monday to Wednesday is 12 + 18 + 21 = <<12+18+21=51>>51 miles.
What is the average distance traveled per day? ** So the average distance traveled per day is 51/3 = <<51/3=17>>17 miles.
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