The advertisement shows the cost of buying pens from a bookstore.
- Gwen bought 21 pens. How much did she pay?
- David bought 60 pens. How much did he pay?
(a)
Number of sets of 15 pens
= 21 ÷ 15
= 1 r 6
Cost of first 15 pens
= 15 x 2.90
= $43.50
Cost of the next 6 pens
= 6 x 2.70
= $16.20
Amount that Gwen paid
= 43.50 + 16.20
= $59.70
(b)
Number of pens that was not part of the first 15 pens
= 60 - 15
= 45
Cost of first 15 pens = $43.50
Cost of the next 45 pens
= 45 x 2.70
= $121.50
Total cost of 60 pens before an additional discount of 7% is applied
= 43.50 + 121.50
= $165
Amount that David paid in percent after an additional discount of 7% is applied
= 100% - 7%
= 93%
100% of the total cost of 60 pens = 165
1% of the total cost of 60 pens = 165 ÷ 100 = 1.65
93% of the total cost of 60 pens = 93 x 1.65 = 153.45
Amount that David paid = $153.45
Answer(s): (a) $59.70; (b) $153.45