Final answer:
Avery would walk a total of 16.2 miles in 15 days.
Step-by-step explanation:
To find the total amount Avery would walk in 15 days, we need to calculate how many miles he walks on a regular day and how many miles he walks on the one day a week when he only walks 1.2 miles.
Avery walks 2.5 miles per day for 6 days a week, so in 6 days he walks 2.5 * 6 = 15 miles.
On the seventh day, he walks 1.2 miles.
Therefore, in 15 days, Avery would walk a total of 15 + 1.2 = 16.2 miles.