Find the start time

Count back from the end time. Write the answer as hours and minutes.

1. A class ends at 7:45 and lasts 30 minutes. What time did it start?
2. A class ends at 8:15 and lasts 15 minutes. What time did it start?
3. A class ends at 10:25 and lasts 25 minutes. What time did it start?
4. A class ends at 9:45 and lasts 25 minutes. What time did it start?
5. A class ends at 12:00 and lasts 40 minutes. What time did it start?
6. A class ends at 12:15 and lasts 45 minutes. What time did it start?
7. A class ends at 11:15 and lasts 35 minutes. What time did it start?
8. A class ends at 2:20 and lasts 50 minutes. What time did it start?
9. A class ends at 8:20 and lasts 40 minutes. What time did it start?
10. A class ends at 2:40 and lasts 35 minutes. What time did it start?
11. A class ends at 1:25 and lasts 110 minutes. What time did it start?
12. A class ends at 12:15 and lasts 35 minutes. What time did it start?
13. A class ends at 7:03 and lasts 58 minutes. What time did it start?
14. A class ends at 1:41 and lasts 15 minutes. What time did it start?
15. A class ends at 12:35 and lasts 19 minutes. What time did it start?
16. A class ends at 10:03 and lasts 32 minutes. What time did it start?
17. A class ends at 9:53 and lasts 103 minutes. What time did it start?
18. A class ends at 9:24 and lasts 140 minutes. What time did it start?
19. A class ends at 4:11 and lasts 163 minutes. What time did it start?
20. A class ends at 4:29 and lasts 98 minutes. What time did it start?