Question 706421
Virginia's parents gave her money to put in her cafeteria account at the beginning of the school year. The function f (s) = 60 – 2.5s describes the amount remaining in her account after she had purchased lunch for s school days. How many days had she eaten in the lunchroom when her account balance was $27.50? 
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Given:
f(s) = 60 – 2.5s
set f(s) to 27.50 and solve for s:
27.50 = 60 – 2.5s
-32.5 = –2.5s
32.5 = 2.5s
32.5/2.5 = s
13 days = s