The advertisement shows the cost of buying files from a shop.
- Anna bought 19 files. How much did she pay?
- Charlie bought 70 files. How much did he pay?
(a)
Number of sets of 15 files
= 19 ÷ 15
= 1 r 4
Cost of first 15 files
= 15 x 2.10
= $31.50
Cost of the next 4 files
= 4 x 1.70
= $6.80
Amount that Anna paid
= 31.50 + 6.80
= $38.30
(b)
Number of files that was not part of the first 15 files
= 70 - 15
= 55
Cost of first 15 files = $31.50
Cost of the next 55 files
= 55 x 1.70
= $93.50
Total cost of 70 files before an additional discount of 10% is applied
= 31.50 + 93.50
= $125
Amount that Charlie paid in percent after an additional discount of 10% is applied
= 100% - 10%
= 90%
100% of the total cost of 70 files = 125
1% of the total cost of 70 files = 125 ÷ 100 = 1.25
90% of the total cost of 70 files = 90 x 1.25 = 112.50
Amount that Charlie paid = $112.50
Answer(s): (a) $38.30; (b) $112.50
