PSLE
A store is having a book sale. The 1st book is at 15% discount. The 2nd book is at 20% discount. The price of the 2nd book should be equal or lower than the price of the 1st book.

1. Risa's books were priced at $23 and $23. How much less did she pay for the 2nd book than the 1st book? 
2. Neave paid a total of $47.95 for his two books. He paid $4.75 more for the 1st book than for the 2nd book. What was the price of the 1st book before discount? 

	1st book	2nd book	Total amount
Original price	100% $23	100% $23
Discount	- 15%	- 20%
Sale price	85%	80%	?

(a)
Selling price of the 1st book
= 85% x 23
= ⁸⁵₁₀₀ x 23
= $19.55

Selling price of 2nd book
= 80% x 23
= ⁸⁰₁₀₀ x 23
= $18.40

Amount that Risa paid less for the 2nd book than the 1st book
= 19.55 - 18.40
= $1.15

	1st book	2nd book	Total amount
Original price	100%	100%
Discount	- 15%	- 20%
Sale price	85%	80%
Compare 1st book and 2nd book	1 u + $4.75	1 u	$47.95

(b)
Sale price of the 1st book = 1 u + 4.75
Sale price of the 2nd book = 1 u

Total amount that Neave paid
= 1 u + 4.75 + 1 u
= 2 u + 4.75

2 u + 4.75 = 47.95
2 u = 47.95 - 4.75
2 u = 43.20

1 u = 43.20 ÷ 2 = 21.60

Sale price of the 1st book
= 1 u + 4.75
= $26.35

85% of the price = $26.35
100% of the price = ^26.35₈₅ x 100 = $31

Selling price of the 1st book before discount = $31

Answer(s): (a) $1.15; (b) $31