PSLE
A stationery shop is having a book sale. The 1st book is at 5% 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. Shannon's books were priced at $22 and $27. How much less did she pay for the 2nd book than the 1st book? 
2. Zeph paid a total of $40.90 for his two books. He paid $12.30 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% $27	100% $22
Discount	- 5%	- 35%
Sale price	95%	65%	?

(a)
Selling price of the 1st book
= 95% x 27
= ⁹⁵₁₀₀ x 27
= $25.65

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

Amount that Shannon paid less for the 2nd book than the 1st book
= 25.65 - 14.30
= $11.35

	1st book	2nd book	Total amount
Original price	100%	100%
Discount	- 5%	- 35%
Sale price	95%	65%
Compare 1st book and 2nd book	1 u + $12.30	1 u	$40.90

(b)
Sale price of the 1st book = 1 u + 12.30
Sale price of the 2nd book = 1 u

Total amount that Zeph paid
= 1 u + 12.30 + 1 u
= 2 u + 12.30

2 u + 12.30 = 40.90
2 u = 40.90 - 12.30
2 u = 28.60

1 u = 28.60 ÷ 2 = 14.30

Sale price of the 1st book
= 1 u + 12.30
= $26.60

95% of the price = $26.60
100% of the price = ^26.60₉₅ x 100 = $28

Selling price of the 1st book before discount = $28

Answer(s): (a) $11.35; (b) $28