Answer:
Since it’s as an estimation it’d be 12km.
Your just adding 2.5 miles to 5 miles. 2.5 miles is half of 5 miles so that’d equally be half of 8 kilometers. Which is 4 kilometers.
Add the 5 mile equivalent of 8 kilometers to the 2.5 mile equivalent of 4 kilometers, and you get 12km as an estimate.