Explain how to solve this problem.

hong went shopping after she woke up. it took hong 20 minutes to get ready to go shopping. she shopped for 45 minutes and then spent 40 minutes eating a snack. then she talked on the phone with her friends for 30 minutes. she finished talking to her friends at 10: 40 a. m.

what time did hong wake up?

a.
work backward.
hong started talking with her friends at 10: 10.
hong started eating at 9: 30.
hong started shopping at 8: 45.
hong woke up at 8: 25.

b.
work backward.
hong started talking with her friends at 10: 40.
hong started eating at 11: 10.
hong started shopping at 11: 50.
hong woke up at 12: 25.

c.
work backward.
hong started talking with her friends at 10: 20.
hong started eating at 9: 40.
hong started shopping at 8: 55.
hong woke up at 8: 35