Answer:
By Day 10
Explanation:
Day 1: 12 + 8 = 20
Day 2: 12 + 8 + 20 = 40
Day 3: 12 + 8 + 40 = 60
Day 4: 12 + 8 + 60 = 80
Day 5: 12 + 8 + 80 = 100
Day 6: 12 + 8 + 100 = 120
Day 7: 12 + 8 + 120 = 140
Day 8: 12 + 8 + 140 = 160
Day 9: 12 + 8 + 160 = 180
Day 10: 12 + 8 + 180 = 200
So they were 195 kilometers away before the 10th day ended.