PSLE
A stationery shop is having a book sale. The 1st book is at 20% 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. Usha's books were priced at $34 and $38. How much more did she pay for the 1st book than the 2nd book? 
2. Harry paid a total of $29.15 for his two books. He paid $4.45 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% $38	100% $34
Discount	- 20%	- 35%
Sale price	80%	65%	?

(a)
Selling price of the 1st book
= 80% x 38
= ⁸⁰₁₀₀ x 38
= $30.40

Selling price of 2nd book
= 65% x 34
= ⁶⁵₁₀₀ x 34
= $22.10

Amount that Usha paid more for the 1st book than the 2nd book
= 30.40 - 22.10
= $8.30

	1st book	2nd book	Total amount
Original price	100%	100%
Discount	- 20%	- 35%
Sale price	80%	65%
Compare 1st book and 2nd book	1 u + $4.45	1 u	$29.15

(b)
Sale price of the 1st book = 1 u + 4.45
Sale price of the 2nd book = 1 u

Total amount that Harry paid
= 1 u + 4.45 + 1 u
= 2 u + 4.45

2 u + 4.45 = 29.15
2 u = 29.15 - 4.45
2 u = 24.70

1 u = 24.70 ÷ 2 = 12.35

Sale price of the 1st book
= 1 u + 4.45
= $16.80

80% of the price = $16.80
100% of the price = ^16.80₈₀ x 100 = $21

Selling price of the 1st book before discount = $21

Answer(s): (a) $8.30; (b) $21