PSLE
A book shop is having a book sale. The 1st book is at 15% discount. The 2nd book is at 35% discount. The price of the 2nd book should be equal or lower than the price of the 1st book.

1. Dana's books were priced at $22 and $32. How much less did she pay for the 2nd book than the 1st book? 
2. Gabriel paid a total of $39.15 for his two books. He paid $11.85 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% $32	100% $22
Discount	- 15%	- 35%
Sale price	85%	65%	?

(a)
Selling price of the 1st book
= 85% x 32
= ⁸⁵₁₀₀ x 32
= $27.20

Selling price of 2nd book
= 65% x 22
= ⁶⁵₁₀₀ x 22
= $14.30

Amount that Dana paid less for the 2nd book than the 1st book
= 27.20 - 14.30
= $12.90

	1st book	2nd book	Total amount
Original price	100%	100%
Discount	- 15%	- 35%
Sale price	85%	65%
Compare 1st book and 2nd book	1 u + $11.85	1 u	$39.15

(b)
Sale price of the 1st book = 1 u + 11.85
Sale price of the 2nd book = 1 u

Total amount that Gabriel paid
= 1 u + 11.85 + 1 u
= 2 u + 11.85

2 u + 11.85 = 39.15
2 u = 39.15 - 11.85
2 u = 27.30

1 u = 27.30 ÷ 2 = 13.65

Sale price of the 1st book
= 1 u + 11.85
= $25.50

85% of the price = $25.50
100% of the price = ^25.50₈₅ x 100 = $30

Selling price of the 1st book before discount = $30

Answer(s): (a) $12.90; (b) $30