PSLE
A store is having a book sale. The 1st book is at 5% 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. Jane's books were priced at $9 and $17. How much more did she pay for the 1st book than the 2nd book? 
2. Valen paid a total of $30.30 for his two books. He paid $13.40 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% $17	100% $9
Discount	- 5%	- 35%
Sale price	95%	65%	?

(a)
Selling price of the 1st book
= 95% x 17
= ⁹⁵₁₀₀ x 17
= $16.15

Selling price of 2nd book
= 65% x 9
= ⁶⁵₁₀₀ x 9
= $5.85

Amount that Jane paid more for the 1st book than the 2nd book
= 16.15 - 5.85
= $10.30

	1st book	2nd book	Total amount
Original price	100%	100%
Discount	- 5%	- 35%
Sale price	95%	65%
Compare 1st book and 2nd book	1 u + $13.40	1 u	$30.30

(b)
Sale price of the 1st book = 1 u + 13.40
Sale price of the 2nd book = 1 u

Total amount that Valen paid
= 1 u + 13.40 + 1 u
= 2 u + 13.40

2 u + 13.40 = 30.30
2 u = 30.30 - 13.40
2 u = 16.90

1 u = 16.90 ÷ 2 = 8.45

Sale price of the 1st book
= 1 u + 13.40
= $21.85

95% of the price = $21.85
100% of the price = ^21.85₉₅ x 100 = $23

Selling price of the 1st book before discount = $23

Answer(s): (a) $10.30; (b) $23