PSLE
A shop is having a book sale. The 1st book is at 25% discount. The 2nd book is at 40% discount. The price of the 2nd book should be equal or lower than the price of the 1st book.

1. Gwen's books were priced at $18 and $18. How much more did she pay for the 1st book than the 2nd book? 
2. Japheth paid a total of $33.15 for his two books. He paid $10.35 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% $18	100% $18
Discount	- 25%	- 40%
Sale price	75%	60%	?

(a)
Selling price of the 1st book
= 75% x 18
= ⁷⁵₁₀₀ x 18
= $13.50

Selling price of 2nd book
= 60% x 18
= ⁶⁰₁₀₀ x 18
= $10.80

Amount that Gwen paid more for the 1st book than the 2nd book
= 13.50 - 10.80
= $2.70

	1st book	2nd book	Total amount
Original price	100%	100%
Discount	- 25%	- 40%
Sale price	75%	60%
Compare 1st book and 2nd book	1 u + $10.35	1 u	$33.15

(b)
Sale price of the 1st book = 1 u + 10.35
Sale price of the 2nd book = 1 u

Total amount that Japheth paid
= 1 u + 10.35 + 1 u
= 2 u + 10.35

2 u + 10.35 = 33.15
2 u = 33.15 - 10.35
2 u = 22.80

1 u = 22.80 ÷ 2 = 11.40

Sale price of the 1st book
= 1 u + 10.35
= $21.75

75% of the price = $21.75
100% of the price = ^21.75₇₅ x 100 = $29

Selling price of the 1st book before discount = $29

Answer(s): (a) $2.70; (b) $29