Add up the lengths of these two runs and then convert the result into km:
4 3/4 miles + 2 1/5 miles = 4 15/20 miles + 2 4/20 miles = 6 19/20 miles.
Writing this as an improper fraction:
139 mi
6 19/20 miles --------------
20
Now convert 139/20 mi into km:
139 mi 1 km 139 km
--------- * ---------- = -------------- = 11.2 km (answer)
20 0.62 mi 12.4