Question

Annika borrowed a book from the library and forgot to return it on time. The library charges $0.25 per day for the first four days and $0.30 per day for all of the remaining days. If Annika had to pay the library $4.00, how many days late was her book?

Answer 1

4-1 = $3 for all the days after day 4. That is ten more days so 14 days total

Answer 2

For 4 days price is 4 ∙ $0.25 = $1

number of days = d

For the total charge after 4 days would be $1 + $0.3 ( d - 4 )

That's because the number of days after the fourth day is d - 4

Set this expression equal to $4 and solve for d:

1+ 0.3 ( d - 4 ) = 4

1 + 0.3 d - 1.2 = 4

0.3 d - 0.2 = 4

Add 0.2 to both sides:

0.3 d = 4.2

Divide both sides by 0.3

d = 4.2 / 0.3 = 14

Answer 3

If you were doing this problem, how would you explain it?