She needs 45 minutes to get ready in the morning (shower, breakfast, etc). Of her class starts at 9:45 AM, what is the latest time she can wake up?

Question

It takes Linda 30 minutes to get to class from her house. She needs 45 minutes to get ready in the morning (shower, breakfast, etc). Of her class starts at 9:45 AM, what is the latest time she can wake up?

Answer 1

I chose to solve this problem by adding the time it takes for Linda to get ready to the time it takes to travel from her home to school.

45 minutes to get ready

+30 minutes to travel from home to school

-------

75 minutes or 1 hour 15 minutes

Once this sum is found, then you subtract that from the class start time to determine the latest time she can wake up.

9:45

-1:15

---------

8:30am

Answer 2

It is easy to take the class start time and work backwards (note: you might subtract or add in different order).

9:45 AM "class starts at 9:45 AM

- 0:30 "30 minutes to get to class from her house"

9:15 AM [latest time to leave her house]

- 0:45 "45 minutes to get ready"

8:30 AM [she must wake up by this time]