PSLE
A store is having a book sale. The 1st book is at 15% discount. The 2nd book is at 30% discount. The price of the 2nd book should be equal or lower than the price of the 1st book.

1. Mary's books were priced at $21 and $29. How much more did she pay for the 1st book than the 2nd book? 
2. Albert paid a total of $59.05 for his two books. He paid $7.25 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% $29	100% $21
Discount	- 15%	- 30%
Sale price	85%	70%	?

(a)
Selling price of the 1st book
= 85% x 29
= ⁸⁵₁₀₀ x 29
= $24.65

Selling price of 2nd book
= 70% x 21
= ⁷⁰₁₀₀ x 21
= $14.70

Amount that Mary paid more for the 1st book than the 2nd book
= 24.65 - 14.70
= $9.95

	1st book	2nd book	Total amount
Original price	100%	100%
Discount	- 15%	- 30%
Sale price	85%	70%
Compare 1st book and 2nd book	1 u + $7.25	1 u	$59.05

(b)
Sale price of the 1st book = 1 u + 7.25
Sale price of the 2nd book = 1 u

Total amount that Albert paid
= 1 u + 7.25 + 1 u
= 2 u + 7.25

2 u + 7.25 = 59.05
2 u = 59.05 - 7.25
2 u = 51.80

1 u = 51.80 ÷ 2 = 25.90

Sale price of the 1st book
= 1 u + 7.25
= $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) $9.95; (b) $39