PSLE
A bookstore is having a book sale. The 1st book is at 25% discount. The 2nd book is at 30% discount. The price of the 2nd book should be equal or lower than the price of the 1st book.

1. Mary's books were priced at $8 and $13. How much did she pay for them?
2. Glen paid a total of $41.40 for his two books. He paid $3.60 less for the 2nd book than the 1st book. What was the price of the 2nd book before discount? 

	1st book	2nd book	Total amount
Original price	100% $13	100% $8
Discount	- 25%	- 30%
Sale price	75%	70%	?

(a)
Selling price of the 1st book
= 75% x 13
= ⁷⁵₁₀₀ x 13
= $9.75

Selling price of 2nd book
= 70% x 8
= ⁷⁰₁₀₀ x 8
= $5.60

Total amount that Mary paid
= 9.75 + 5.60
= $15.35

	1st book	2nd book	Total amount
Original price	100%	100%
Discount	- 25%	- 30%
Sale price	75%	70%
Compare 1st book and 2nd book	1 u + $3.60	1 u	$41.40

(b)
Sale price of the 1st book = 1 u + 3.60
Sale price of the 2nd book = 1 u

Total amount that Glen paid
= 1 u + 3.60 + 1 u
= 2 u + 3.60

2 u + 3.60 = 41.40
2 u = 41.40 - 3.60
2 u = 37.80

1 u = 37.80 ÷ 2 = 18.90

Sale price of the 2nd book = $18.90

70% of the price = $18.90
100% of the price = ^18.90₇₀ x 100 = $27

Selling price of the 2nd book before discount = $27

Answer(s): (a) $15.35; (b) $27