Answer:
Option (4)
Explanation:
An ordered pair (x, y) represents,
x = number of days that a library book is late
y = Total fee for the delay
Late fee of a library book = $0.30 per day
Then late fee of a book for the delay of 'x' days,
y = per day fee × number of days delayed
y =

Option (1). For (-3, -0.90)
Since number days can't be negative so not the answer.
Option (2). For (-2.5, -0.75)
Number of days are negative so can't be the answer.
Option (3). For (4.5, 1.35)
Fee for 4.5 days will be,
y = 0.30(4) [Since fee is charged after completion of one day or in the midnight]
Fee for 4.5 days will be the same as fee for 4 days.
y = $1.20
Therefore, this option will not be the answer.
Option (4). For (8, 2.40)
y = 0.30x
y = 0.30(8)
y = 2.40
Therefore, option (4) will be the answer.