ANSWER:
Arlene is getting
hours of sleep in a week.
SOLUTION:
Given, Arlene sleeps for seven hours and 20 minutes each night
We need find how many hours of sleep does she get in a week as a mixed number?
Now, total sleeping time for each night is 7 hours and 20 minutes
Let us convert hours in to minutes first and then in last we can convert it again to hours.
Sleeping time per one night = 7 hours + 20 minutes
= 7 x 60 minutes + 20 minutes
= 420 + 20 minutes
= 440 minutes
Now, sleeping time per one week = sleeping time per one night x 7 nights
= 440 x 7
= 3080 minutes
Now, sleeping time per week in hours =

[20 is remainder]

Hence Arlene is getting
hours of sleep in a week.