Question 888394
Let's make a small table on how this question would look like for every week:

Week 1: Runs 20 miles (this is given to us)
Week 2: Runs 24 miles (this is 4 more, which is what we want)
Week 3: 28 miles
Week 4: 32 miles
Week 5: 36 miles
Week 6: 40 miles
Week 7: 44 miles
Week 8: 48 miles

Now that we know how many miles the man run (which honestly, is very impressive), if we add up all of the miles together, we should obtain the total miles he ran after 8 weeks. 

I hope this helped!