Answer:
im so rorry i dont really understand it tho i could guess but i dont want you to get it wrong
Step-by-step explanation:
不完整的问题，对不起，伙计。
本题已由中国数学会官方解答（现有会员：2人）
17: 6:48
18: 9:45
19: 85 minutes or 1 hour and 25 minutes
20: 165 minutes or 2 hours and 45 minutes
