PSLE
A stationery shop is having a book sale. The 1st book is at 5% discount. The 2nd book is at 15% discount. The price of the 2nd book should be equal or lower than the price of the 1st book.

1. Nicole's books were priced at $12 and $15. How much less did she pay for the 2nd book than the 1st book? 
2. Perry paid a total of $49.10 for his two books. He paid $11.70 more for the 1st book than for the 2nd book. What was the price of the 1st book before discount? 

	1st book	2nd book	Total amount
Original price	100% $15	100% $12
Discount	- 5%	- 15%
Sale price	95%	85%	?

(a)
Selling price of the 1st book
= 95% x 15
= ⁹⁵₁₀₀ x 15
= $14.25

Selling price of 2nd book
= 85% x 12
= ⁸⁵₁₀₀ x 12
= $10.20

Amount that Nicole paid less for the 2nd book than the 1st book
= 14.25 - 10.20
= $4.05

	1st book	2nd book	Total amount
Original price	100%	100%
Discount	- 5%	- 15%
Sale price	95%	85%
Compare 1st book and 2nd book	1 u + $11.70	1 u	$49.10

(b)
Sale price of the 1st book = 1 u + 11.70
Sale price of the 2nd book = 1 u

Total amount that Perry paid
= 1 u + 11.70 + 1 u
= 2 u + 11.70

2 u + 11.70 = 49.10
2 u = 49.10 - 11.70
2 u = 37.40

1 u = 37.40 ÷ 2 = 18.70

Sale price of the 1st book
= 1 u + 11.70
= $30.40

95% of the price = $30.40
100% of the price = ^30.40₉₅ x 100 = $32

Selling price of the 1st book before discount = $32

Answer(s): (a) $4.05; (b) $32