PSLE
A store is having a book sale. The 1st book is at 20% discount. The 2nd book is at 35% discount. The price of the 2nd book should be equal or lower than the price of the 1st book.

1. Marion's books were priced at $18 and $33. How much did she pay for them?
2. Ahmad paid a total of $39.30 for his two books. He paid $5.50 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% $33	100% $18
Discount	- 20%	- 35%
Sale price	80%	65%	?

(a)
Selling price of the 1st book
= 80% x 33
= ⁸⁰₁₀₀ x 33
= $26.40

Selling price of 2nd book
= 65% x 18
= ⁶⁵₁₀₀ x 18
= $11.70

Total amount that Marion paid
= 26.40 + 11.70
= $38.10

	1st book	2nd book	Total amount
Original price	100%	100%
Discount	- 20%	- 35%
Sale price	80%	65%
Compare 1st book and 2nd book	1 u + $5.50	1 u	$39.30

(b)
Sale price of the 1st book = 1 u + 5.50
Sale price of the 2nd book = 1 u

Total amount that Ahmad paid
= 1 u + 5.50 + 1 u
= 2 u + 5.50

2 u + 5.50 = 39.30
2 u = 39.30 - 5.50
2 u = 33.80

1 u = 33.80 ÷ 2 = 16.90

Sale price of the 2nd book = $16.90

65% of the price = $16.90
100% of the price = ^16.90₆₅ x 100 = $26

Selling price of the 2nd book before discount = $26

Answer(s): (a) $38.10; (b) $26