Answer:
405.80
Explanation:
So, we know Carlos ran 21 miles per week, for 12 weeks....
That makes 21 mi/wk x 12 weeks = 252 miles.
Then we know each km is 0.621 mile.
So, we divide 252 miles by 0.621 mile/km to get= 405.80 km
Dividing miles by miles/km gives us the unit we want (km).
There was a trap in this question, because if instead of dividing the 252 miles by 0.621 you would have multiplied it, you would have gotten another answer listed... just not the right one. :-)