PSLE
A bookstore is having a book sale. The 1st book is at 5% discount. The 2nd book is at 15% discount. The price of the 2nd book should be equal or lower than the price of the 1st book.

1. Kathy's books were priced at $23 and $29. How much did she pay for them?
2. George paid a total of $36.10 for his two books. He paid $3.80 more for the 1st book than the 2nd book. What was the price of the 2nd book before discount? 

	1st book	2nd book	Total amount
Original price	100% $29	100% $23
Discount	- 5%	- 15%
Sale price	95%	85%	?

(a)
Selling price of the 1st book
= 95% x 29
= ⁹⁵₁₀₀ x 29
= $27.55

Selling price of 2nd book
= 85% x 23
= ⁸⁵₁₀₀ x 23
= $19.55

Total amount that Kathy paid
= 27.55 + 19.55
= $47.10

	1st book	2nd book	Total amount
Original price	100%	100%
Discount	- 5%	- 15%
Sale price	95%	85%
Compare 1st book and 2nd book	1 u + $3.80	1 u	$36.10

(b)
Sale price of the 1st book = 1 u + 3.80
Sale price of the 2nd book = 1 u

Total amount that George paid
= 1 u + 3.80 + 1 u
= 2 u + 3.80

2 u + 3.80 = 36.10
2 u = 36.10 - 3.80
2 u = 32.30

1 u = 32.30 ÷ 2 = 16.15

Sale price of the 2nd book = $16.15

85% of the price = $16.15
100% of the price = ^16.15₈₅ x 100 = $19

Selling price of the 2nd book before discount = $19

Answer(s): (a) $47.10; (b) $19