PSLE
A store is having a book sale. The 1st book is at 10% discount. The 2nd book is at 15% discount. The price of the 2nd book should be equal or lower than the price of the 1st book.

1. Sabrina's books were priced at $26 and $36. How much did she pay for them?
2. Xavier paid a total of $40.50 for his two books. He paid $9.90 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% $36	100% $26
Discount	- 10%	- 15%
Sale price	90%	85%	?

(a)
Selling price of the 1st book
= 90% x 36
= ⁹⁰₁₀₀ x 36
= $32.40

Selling price of 2nd book
= 85% x 26
= ⁸⁵₁₀₀ x 26
= $22.10

Total amount that Sabrina paid
= 32.40 + 22.10
= $54.50

	1st book	2nd book	Total amount
Original price	100%	100%
Discount	- 10%	- 15%
Sale price	90%	85%
Compare 1st book and 2nd book	1 u + $9.90	1 u	$40.50

(b)
Sale price of the 1st book = 1 u + 9.90
Sale price of the 2nd book = 1 u

Total amount that Xavier paid
= 1 u + 9.90 + 1 u
= 2 u + 9.90

2 u + 9.90 = 40.50
2 u = 40.50 - 9.90
2 u = 30.60

1 u = 30.60 ÷ 2 = 15.30

Sale price of the 2nd book = $15.30

85% of the price = $15.30
100% of the price = ^15.30₈₅ x 100 = $18

Selling price of the 2nd book before discount = $18

Answer(s): (a) $54.50; (b) $18