Answer: the school paid $80 for the book.
Step-by-step explanation:
Let x represent the amount that the school paid for the book.
Her school charges a lost book fee equal to 75% of the cost of the book. It means that the amount that the school would charge on a book that cost $x is
75/100 × x = 0.75 × x = 0.75x
Sarah received a notice stating that she owed the school $60 for he lost book. It means that
0.75x = 60
x = 60/0.75
x = $80