PSLE
A stationery kiosk is having a book sale. The 1st book is at 15% 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. Joelle's books were priced at $21 and $25. How much did she pay for them?
2. Charlie paid a total of $29.90 for his two books. He paid $7.50 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% $25	100% $21
Discount	- 15%	- 30%
Sale price	85%	70%	?

(a)
Selling price of the 1st book
= 85% x 25
= ⁸⁵₁₀₀ x 25
= $21.25

Selling price of 2nd book
= 70% x 21
= ⁷⁰₁₀₀ x 21
= $14.70

Total amount that Joelle paid
= 21.25 + 14.70
= $35.95

	1st book	2nd book	Total amount
Original price	100%	100%
Discount	- 15%	- 30%
Sale price	85%	70%
Compare 1st book and 2nd book	1 u + $7.50	1 u	$29.90

(b)
Sale price of the 1st book = 1 u + 7.50
Sale price of the 2nd book = 1 u

Total amount that Charlie paid
= 1 u + 7.50 + 1 u
= 2 u + 7.50

2 u + 7.50 = 29.90
2 u = 29.90 - 7.50
2 u = 22.40

1 u = 22.40 ÷ 2 = 11.20

Sale price of the 2nd book = $11.20

70% of the price = $11.20
100% of the price = ^11.20₇₀ x 100 = $16

Selling price of the 2nd book before discount = $16

Answer(s): (a) $35.95; (b) $16