Answer
$960 per month on her entertainment budget
Step-by-step explanation
If Amy decides to live with her parents or a relative, she will save $8,640 compared to living on campus over the 9-month period ($12,798 living on campus minus $4,158 living with a relative).
Since we are wondering what she can now use for entertainment each month, we divide the number of dollars saved from living with a relative by 9 months.
$8,640 / 9 months = $960 per month
Amy is now able to reallocate $960 per month on her entertainment budget since she currently doesn't have an entertainment budget listed.