James injured his ankle and decides to slowly start working back up to his previous running goals and then surpass them.  Before the injury, he was able to run 100 miles per week.  He wants to get up to 20% more than that total in 280 days and each week he will increase miles walked in the week by the same amount.  How many miles does he need to add per week?
He wants to run 100*.2=<<100*.2=20>>20 miles more than he used to
So he needs to run 100+20=<<100+20=120>>120 miles
He is doing this in 280/7=<<280/7=40>>40 weeks
So he needs to add 120/40=<<120/40=3>>3 miles per week
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