PSLE
A stationery 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. Yoko's books were priced at $14 and $25. How much did she pay for them?
2. David paid a total of $39.90 for his two books. He paid $11.10 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% $25	100% $14
Discount	- 25%	- 40%
Sale price	75%	60%	?

(a)
Selling price of the 1st book
= 75% x 25
= ⁷⁵₁₀₀ x 25
= $18.75

Selling price of 2nd book
= 60% x 14
= ⁶⁰₁₀₀ x 14
= $8.40

Total amount that Yoko paid
= 18.75 + 8.40
= $27.15

	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 + $11.10	1 u	$39.90

(b)
Sale price of the 1st book = 1 u + 11.10
Sale price of the 2nd book = 1 u

Total amount that David paid
= 1 u + 11.10 + 1 u
= 2 u + 11.10

2 u + 11.10 = 39.90
2 u = 39.90 - 11.10
2 u = 28.80

1 u = 28.80 ÷ 2 = 14.40

Sale price of the 2nd book = $14.40

60% of the price = $14.40
100% of the price = ^14.40₆₀ x 100 = $24

Selling price of the 2nd book before discount = $24

Answer(s): (a) $27.15; (b) $24