PSLE
A bookstore is having a book sale. The 1st book is at 5% 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. Xandra's books were priced at $8 and $21. How much more did she pay for the 1st book than the 2nd book? 
2. Zeph paid a total of $33.25 for his two books. He paid $10.45 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% $21	100% $8
Discount	- 5%	- 40%
Sale price	95%	60%	?

(a)
Selling price of the 1st book
= 95% x 21
= ⁹⁵₁₀₀ x 21
= $19.95

Selling price of 2nd book
= 60% x 8
= ⁶⁰₁₀₀ x 8
= $4.80

Amount that Xandra paid more for the 1st book than the 2nd book
= 19.95 - 4.80
= $15.15

	1st book	2nd book	Total amount
Original price	100%	100%
Discount	- 5%	- 40%
Sale price	95%	60%
Compare 1st book and 2nd book	1 u + $10.45	1 u	$33.25

(b)
Sale price of the 1st book = 1 u + 10.45
Sale price of the 2nd book = 1 u

Total amount that Zeph paid
= 1 u + 10.45 + 1 u
= 2 u + 10.45

2 u + 10.45 = 33.25
2 u = 33.25 - 10.45
2 u = 22.80

1 u = 22.80 ÷ 2 = 11.40

Sale price of the 1st book
= 1 u + 10.45
= $21.85

95% of the price = $21.85
100% of the price = ^21.85₉₅ x 100 = $23

Selling price of the 1st book before discount = $23

Answer(s): (a) $15.15; (b) $23