12 kilometers
= (12×1000) meters
=12000 meters
since its 400 meters per lap, we divide the total distance by 400 meters to determine how many laps is required by Kali
12000 meters ÷ 400 meters = 30 laps
Then, we divide 30 laps by the amount of laps he runs a day (10 laps) to get the number of days
30 ÷ 10 = 3 days