PSLE
A stationery shop is having a book sale. The 1st book is at 15% discount. The 2nd book is at 25% discount. The price of the 2nd book should be equal or lower than the price of the 1st book.

1. Shannon's books were priced at $35 and $37. How much less did she pay for the 2nd book than the 1st book? 
2. Howard paid a total of $56.40 for his two books. He paid $9.90 less for the 2nd book than for the 1st book. What was the price of the 1st book before discount? 

	1st book	2nd book	Total amount
Original price	100% $37	100% $35
Discount	- 15%	- 25%
Sale price	85%	75%	?

(a)
Selling price of the 1st book
= 85% x 37
= ⁸⁵₁₀₀ x 37
= $31.45

Selling price of 2nd book
= 75% x 35
= ⁷⁵₁₀₀ x 35
= $26.25

Amount that Shannon paid less for the 2nd book than the 1st book
= 31.45 - 26.25
= $5.20

	1st book	2nd book	Total amount
Original price	100%	100%
Discount	- 15%	- 25%
Sale price	85%	75%
Compare 1st book and 2nd book	1 u + $9.90	1 u	$56.40

(b)
Sale price of the 1st book = 1 u + 9.90
Sale price of the 2nd book = 1 u

Total amount that Howard paid
= 1 u + 9.90 + 1 u
= 2 u + 9.90

2 u + 9.90 = 56.40
2 u = 56.40 - 9.90
2 u = 46.50

1 u = 46.50 ÷ 2 = 23.25

Sale price of the 1st book
= 1 u + 9.90
= $33.15

85% of the price = $33.15
100% of the price = ^33.15₈₅ x 100 = $39

Selling price of the 1st book before discount = $39

Answer(s): (a) $5.20; (b) $39