PSLE
A shop 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. Xylia's books were priced at $1 and $12. How much more did she pay for the 1st book than the 2nd book? 
2. Daniel paid a total of $41.30 for his two books. He paid $2.90 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% $12	100% $1
Discount	- 15%	- 20%
Sale price	85%	80%	?

(a)
Selling price of the 1st book
= 85% x 12
= ⁸⁵₁₀₀ x 12
= $10.20

Selling price of 2nd book
= 80% x 1
= ⁸⁰₁₀₀ x 1
= $0.80

Amount that Xylia paid more for the 1st book than the 2nd book
= 10.20 - 0.80
= $9.40

	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 + $2.90	1 u	$41.30

(b)
Sale price of the 1st book = 1 u + 2.90
Sale price of the 2nd book = 1 u

Total amount that Daniel paid
= 1 u + 2.90 + 1 u
= 2 u + 2.90

2 u + 2.90 = 41.30
2 u = 41.30 - 2.90
2 u = 38.40

1 u = 38.40 ÷ 2 = 19.20

Sale price of the 1st book
= 1 u + 2.90
= $22.10

85% of the price = $22.10
100% of the price = ^22.10₈₅ x 100 = $26

Selling price of the 1st book before discount = $26

Answer(s): (a) $9.40; (b) $26