PSLE
A store is having a book sale. The 1st book is at 5% discount. The 2nd book is at 15% discount. The price of the 2nd book should be equal or lower than the price of the 1st book.

1. Kylie's books were priced at $9 and $24. How much did she pay for them?
2. Seth paid a total of $30.15 for his two books. He paid $9.75 more for the 1st book than the 2nd book. What was the price of the 2nd book before discount? 

	1st book	2nd book	Total amount
Original price	100% $24	100% $9
Discount	- 5%	- 15%
Sale price	95%	85%	?

(a)
Selling price of the 1st book
= 95% x 24
= ⁹⁵₁₀₀ x 24
= $22.80

Selling price of 2nd book
= 85% x 9
= ⁸⁵₁₀₀ x 9
= $7.65

Total amount that Kylie paid
= 22.80 + 7.65
= $30.45

	1st book	2nd book	Total amount
Original price	100%	100%
Discount	- 5%	- 15%
Sale price	95%	85%
Compare 1st book and 2nd book	1 u + $9.75	1 u	$30.15

(b)
Sale price of the 1st book = 1 u + 9.75
Sale price of the 2nd book = 1 u

Total amount that Seth paid
= 1 u + 9.75 + 1 u
= 2 u + 9.75

2 u + 9.75 = 30.15
2 u = 30.15 - 9.75
2 u = 20.40

1 u = 20.40 ÷ 2 = 10.20

Sale price of the 2nd book = $10.20

85% of the price = $10.20
100% of the price = ^10.20₈₅ x 100 = $12

Selling price of the 2nd book before discount = $12

Answer(s): (a) $30.45; (b) $12