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. Usha's books were priced at $19 and $31. How much did she pay for them?
2. Ken paid a total of $39.90 for his two books. He paid $11.30 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% $31	100% $19
Discount	- 20%	- 35%
Sale price	80%	65%	?

(a)
Selling price of the 1st book
= 80% x 31
= ⁸⁰₁₀₀ x 31
= $24.80

Selling price of 2nd book
= 65% x 19
= ⁶⁵₁₀₀ x 19
= $12.35

Total amount that Usha paid
= 24.80 + 12.35
= $37.15

	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 + $11.30	1 u	$39.90

(b)
Sale price of the 1st book = 1 u + 11.30
Sale price of the 2nd book = 1 u

Total amount that Ken paid
= 1 u + 11.30 + 1 u
= 2 u + 11.30

2 u + 11.30 = 39.90
2 u = 39.90 - 11.30
2 u = 28.60

1 u = 28.60 ÷ 2 = 14.30

Sale price of the 2nd book = $14.30

65% of the price = $14.30
100% of the price = ^14.30₆₅ x 100 = $22

Selling price of the 2nd book before discount = $22

Answer(s): (a) $37.15; (b) $22