PSLE
A shop is having a book sale. The 1st book is at 5% 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. Anna's books were priced at $29 and $30. How much more did she pay for the 1st book than the 2nd book? 
2. Ethan paid a total of $43.10 for his two books. He paid $6.30 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% $30	100% $29
Discount	- 5%	- 20%
Sale price	95%	80%	?

(a)
Selling price of the 1st book
= 95% x 30
= ⁹⁵₁₀₀ x 30
= $28.50

Selling price of 2nd book
= 80% x 29
= ⁸⁰₁₀₀ x 29
= $23.20

Amount that Anna paid more for the 1st book than the 2nd book
= 28.50 - 23.20
= $5.30

	1st book	2nd book	Total amount
Original price	100%	100%
Discount	- 5%	- 20%
Sale price	95%	80%
Compare 1st book and 2nd book	1 u + $6.30	1 u	$43.10

(b)
Sale price of the 1st book = 1 u + 6.30
Sale price of the 2nd book = 1 u

Total amount that Ethan paid
= 1 u + 6.30 + 1 u
= 2 u + 6.30

2 u + 6.30 = 43.10
2 u = 43.10 - 6.30
2 u = 36.80

1 u = 36.80 ÷ 2 = 18.40

Sale price of the 1st book
= 1 u + 6.30
= $24.70

95% of the price = $24.70
100% of the price = ^24.70₉₅ x 100 = $26

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

Answer(s): (a) $5.30; (b) $26