A book rental shop rented out books and the rate of rental charges are shown in the table.
Number of days |
Rates |
After the first 9 days |
40 cents a day |
After 9 days |
50 cents a day |
Billy rented 2 books and was charged $10.20. How many days did he rent the books for?
$1 = 100¢
$10.20 = 10.20 x 100 = 1020¢
Amount that Billy paid for each book
= 1020 ÷ 2
= 510¢
Amount that Billy paid for each book for renting for the first 9 days
= 9 x 40
= 360¢
Additional amount that Billy paid for each book for renting for additional days
= 510 - 360
= 150¢
Number of additional days that Billy rented for each book
= 150 ÷ 50
= 3
Total number of days that Billy rented the books
= 9 + 3
= 12
Answer(s): 12