PSLE
A store is having a book sale. The 1st book is at 25% 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. Sarah's books were priced at $21 and $25. How much did she pay for them?
2. Xavier paid a total of $45.65 for his two books. He paid $5.35 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% $25	100% $21
Discount	- 25%	- 35%
Sale price	75%	65%	?

(a)
Selling price of the 1st book
= 75% x 25
= ⁷⁵₁₀₀ x 25
= $18.75

Selling price of 2nd book
= 65% x 21
= ⁶⁵₁₀₀ x 21
= $13.65

Total amount that Sarah paid
= 18.75 + 13.65
= $32.40

	1st book	2nd book	Total amount
Original price	100%	100%
Discount	- 25%	- 35%
Sale price	75%	65%
Compare 1st book and 2nd book	1 u + $5.35	1 u	$45.65

(b)
Sale price of the 1st book = 1 u + 5.35
Sale price of the 2nd book = 1 u

Total amount that Xavier paid
= 1 u + 5.35 + 1 u
= 2 u + 5.35

2 u + 5.35 = 45.65
2 u = 45.65 - 5.35
2 u = 40.30

1 u = 40.30 ÷ 2 = 20.15

Sale price of the 2nd book = $20.15

65% of the price = $20.15
100% of the price = ^20.15₆₅ x 100 = $31

Selling price of the 2nd book before discount = $31

Answer(s): (a) $32.40; (b) $31