PSLE
A book shop is having a book sale. The 1st book is at 25% discount. The 2nd book is at 40% discount. The price of the 2nd book should be equal or lower than the price of the 1st book.

1. Cathy's books were priced at $4 and $18. How much did she pay for them?
2. Gabriel paid a total of $43.05 for his two books. He paid $9.45 less for the 2nd book than the 1st book. What was the price of the 2nd book before discount? 

	1st book	2nd book	Total amount
Original price	100% $18	100% $4
Discount	- 25%	- 40%
Sale price	75%	60%	?

(a)
Selling price of the 1st book
= 75% x 18
= ⁷⁵₁₀₀ x 18
= $13.50

Selling price of 2nd book
= 60% x 4
= ⁶⁰₁₀₀ x 4
= $2.40

Total amount that Cathy paid
= 13.50 + 2.40
= $15.90

	1st book	2nd book	Total amount
Original price	100%	100%
Discount	- 25%	- 40%
Sale price	75%	60%
Compare 1st book and 2nd book	1 u + $9.45	1 u	$43.05

(b)
Sale price of the 1st book = 1 u + 9.45
Sale price of the 2nd book = 1 u

Total amount that Gabriel paid
= 1 u + 9.45 + 1 u
= 2 u + 9.45

2 u + 9.45 = 43.05
2 u = 43.05 - 9.45
2 u = 33.60

1 u = 33.60 ÷ 2 = 16.80

Sale price of the 2nd book = $16.80

60% of the price = $16.80
100% of the price = ^16.80₆₀ x 100 = $28

Selling price of the 2nd book before discount = $28

Answer(s): (a) $15.90; (b) $28