PSLE
A store 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. Cindy's books were priced at $28 and $36. How much less did she pay for the 2nd book than the 1st book? 
2. Vaidev paid a total of $33.80 for his two books. He paid $10.40 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% $36	100% $28
Discount	- 15%	- 35%
Sale price	85%	65%	?

(a)
Selling price of the 1st book
= 85% x 36
= ⁸⁵₁₀₀ x 36
= $30.60

Selling price of 2nd book
= 65% x 28
= ⁶⁵₁₀₀ x 28
= $18.20

Amount that Cindy paid less for the 2nd book than the 1st book
= 30.60 - 18.20
= $12.40

	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 + $10.40	1 u	$33.80

(b)
Sale price of the 1st book = 1 u + 10.40
Sale price of the 2nd book = 1 u

Total amount that Vaidev paid
= 1 u + 10.40 + 1 u
= 2 u + 10.40

2 u + 10.40 = 33.80
2 u = 33.80 - 10.40
2 u = 23.40

1 u = 23.40 ÷ 2 = 11.70

Sale price of the 1st book
= 1 u + 10.40
= $22.10

85% of the price = $22.10
100% of the price = ^22.10₈₅ x 100 = $26

Selling price of the 1st book before discount = $26

Answer(s): (a) $12.40; (b) $26