PSLE
A book shop is having a book sale. The 1st book is at 15% discount. The 2nd book is at 25% discount. The price of the 2nd book should be equal or lower than the price of the 1st book.

1. Gillian's books were priced at $22 and $22. How much did she pay for them?
2. Jeremy paid a total of $31.65 for his two books. He paid $9.15 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% $22	100% $22
Discount	- 15%	- 25%
Sale price	85%	75%	?

(a)
Selling price of the 1st book
= 85% x 22
= ⁸⁵₁₀₀ x 22
= $18.70

Selling price of 2nd book
= 75% x 22
= ⁷⁵₁₀₀ x 22
= $16.50

Total amount that Gillian paid
= 18.70 + 16.50
= $35.20

	1st book	2nd book	Total amount
Original price	100%	100%
Discount	- 15%	- 25%
Sale price	85%	75%
Compare 1st book and 2nd book	1 u + $9.15	1 u	$31.65

(b)
Sale price of the 1st book = 1 u + 9.15
Sale price of the 2nd book = 1 u

Total amount that Jeremy paid
= 1 u + 9.15 + 1 u
= 2 u + 9.15

2 u + 9.15 = 31.65
2 u = 31.65 - 9.15
2 u = 22.50

1 u = 22.50 ÷ 2 = 11.25

Sale price of the 2nd book = $11.25

75% of the price = $11.25
100% of the price = ^11.25₇₅ x 100 = $15

Selling price of the 2nd book before discount = $15

Answer(s): (a) $35.20; (b) $15