PSLE
A shop is having a book sale. The 1st book is at 20% 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. Nora's books were priced at $36 and $39. How much did she pay for them?
2. Flynn paid a total of $33.20 for his two books. He paid $11.60 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% $39	100% $36
Discount	- 20%	- 40%
Sale price	80%	60%	?

(a)
Selling price of the 1st book
= 80% x 39
= ⁸⁰₁₀₀ x 39
= $31.20

Selling price of 2nd book
= 60% x 36
= ⁶⁰₁₀₀ x 36
= $21.60

Total amount that Nora paid
= 31.20 + 21.60
= $52.80

	1st book	2nd book	Total amount
Original price	100%	100%
Discount	- 20%	- 40%
Sale price	80%	60%
Compare 1st book and 2nd book	1 u + $11.60	1 u	$33.20

(b)
Sale price of the 1st book = 1 u + 11.60
Sale price of the 2nd book = 1 u

Total amount that Flynn paid
= 1 u + 11.60 + 1 u
= 2 u + 11.60

2 u + 11.60 = 33.20
2 u = 33.20 - 11.60
2 u = 21.60

1 u = 21.60 ÷ 2 = 10.80

Sale price of the 2nd book = $10.80

60% of the price = $10.80
100% of the price = ^10.80₆₀ x 100 = $18

Selling price of the 2nd book before discount = $18

Answer(s): (a) $52.80; (b) $18