The advertisement shows the cost of buying files from a book shop.
- Gillian bought 27 files. How much did she pay?
- Seth bought 70 files. How much did he pay?
(a)
Number of sets of 15 files
= 27 ÷ 15
= 1 r 12
Cost of first 15 files
= 15 x 2.30
= $34.50
Cost of the next 12 files
= 12 x 1.90
= $22.80
Amount that Gillian paid
= 34.50 + 22.80
= $57.30
(b)
Number of files that was not part of the first 15 files
= 70 - 15
= 55
Cost of first 15 files = $34.50
Cost of the next 55 files
= 55 x 1.90
= $104.50
Total cost of 70 files before an additional discount of 9% is applied
= 34.50 + 104.50
= $139
Amount that Seth paid in percent after an additional discount of 9% is applied
= 100% - 9%
= 91%
100% of the total cost of 70 files = 139
1% of the total cost of 70 files = 139 ÷ 100 = 1.39
91% of the total cost of 70 files = 91 x 1.39 = 126.49
Amount that Seth paid = $126.49
Answer(s): (a) $57.30; (b) $126.49