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. Tiffany's books were priced at $16 and $22. How much less did she pay for the 2nd book than the 1st book? 
2. Japheth paid a total of $40.40 for his two books. He paid $12.80 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% $22	100% $16
Discount	- 5%	- 40%
Sale price	95%	60%	?

(a)
Selling price of the 1st book
= 95% x 22
= ⁹⁵₁₀₀ x 22
= $20.90

Selling price of 2nd book
= 60% x 16
= ⁶⁰₁₀₀ x 16
= $9.60

Amount that Tiffany paid less for the 2nd book than the 1st book
= 20.90 - 9.60
= $11.30

	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 + $12.80	1 u	$40.40

(b)
Sale price of the 1st book = 1 u + 12.80
Sale price of the 2nd book = 1 u

Total amount that Japheth paid
= 1 u + 12.80 + 1 u
= 2 u + 12.80

2 u + 12.80 = 40.40
2 u = 40.40 - 12.80
2 u = 27.60

1 u = 27.60 ÷ 2 = 13.80

Sale price of the 1st book
= 1 u + 12.80
= $26.60

95% of the price = $26.60
100% of the price = ^26.60₉₅ x 100 = $28

Selling price of the 1st book before discount = $28

Answer(s): (a) $11.30; (b) $28