Raymond had already run 3 miles on his own, and he expects to run 1 mile during each track practice. How many track practices would it take for Raymond to run 45 miles?
Answer in the number of practices.
Raymond has already run 3 miles on his own. If he expects to run 1 mile during each track practice, then the remaining number of miles he needs to run is 45 - 3 = <<45-3=42>>42 miles.
Therefore, Raymond would need to attend 42 / 1 = <<42/1=42>>42 track practices to run 45 miles. Answer: \boxed{42}.