We don't know!
Maybe he started at one mile a week, and increased that by a mile a week every week, or a mile a week every month. Or maybe he started at 15 miles a week, and increased by three miles a week each week.
There isn't enough information in the question to give a definite answer.
Jeff runs 52 miles a week. How many weeks have passed since he was running 25 miles a week?
2 answers
Thomas is training for a marathon. He runs for 2 miles and then he walks for half a mile. If he trains by running 22 miles everyday how many miles will he walk?