PSLE
A stationery shop is having a book sale. The 1st book is at 10% 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. Sarah's books were priced at $2 and $12. How much more did she pay for the 1st book than the 2nd book? 
2. Lee paid a total of $41.45 for his two books. He paid $8.95 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% $12	100% $2
Discount	- 10%	- 35%
Sale price	90%	65%	?

(a)
Selling price of the 1st book
= 90% x 12
= ⁹⁰₁₀₀ x 12
= $10.80

Selling price of 2nd book
= 65% x 2
= ⁶⁵₁₀₀ x 2
= $1.30

Amount that Sarah paid more for the 1st book than the 2nd book
= 10.80 - 1.30
= $9.50

	1st book	2nd book	Total amount
Original price	100%	100%
Discount	- 10%	- 35%
Sale price	90%	65%
Compare 1st book and 2nd book	1 u + $8.95	1 u	$41.45

(b)
Sale price of the 1st book = 1 u + 8.95
Sale price of the 2nd book = 1 u

Total amount that Lee paid
= 1 u + 8.95 + 1 u
= 2 u + 8.95

2 u + 8.95 = 41.45
2 u = 41.45 - 8.95
2 u = 32.50

1 u = 32.50 ÷ 2 = 16.25

Sale price of the 1st book
= 1 u + 8.95
= $25.20

90% of the price = $25.20
100% of the price = ^25.20₉₀ x 100 = $28

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

Answer(s): (a) $9.50; (b) $28