PSLE
A shop is having a book sale. The 1st book is at 5% discount. The 2nd book is at 10% discount. The price of the 2nd book should be equal or lower than the price of the 1st book.

1. Tiffany's books were priced at $37 and $37. How much less did she pay for the 2nd book than the 1st book? 
2. Warren paid a total of $39.10 for his two books. He paid $10.30 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% $37	100% $37
Discount	- 5%	- 10%
Sale price	95%	90%	?

(a)
Selling price of the 1st book
= 95% x 37
= ⁹⁵₁₀₀ x 37
= $35.15

Selling price of 2nd book
= 90% x 37
= ⁹⁰₁₀₀ x 37
= $33.30

Amount that Tiffany paid less for the 2nd book than the 1st book
= 35.15 - 33.30
= $1.85

	1st book	2nd book	Total amount
Original price	100%	100%
Discount	- 5%	- 10%
Sale price	95%	90%
Compare 1st book and 2nd book	1 u + $10.30	1 u	$39.10

(b)
Sale price of the 1st book = 1 u + 10.30
Sale price of the 2nd book = 1 u

Total amount that Warren paid
= 1 u + 10.30 + 1 u
= 2 u + 10.30

2 u + 10.30 = 39.10
2 u = 39.10 - 10.30
2 u = 28.80

1 u = 28.80 ÷ 2 = 14.40

Sale price of the 1st book
= 1 u + 10.30
= $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) $1.85; (b) $26