PSLE
A bookstore is having a book sale.

The 1st book is at 10% discount.
The 2nd book is at 20% discount.
The price of the 2nd book should be equal or lower than the price of the 1st book.

Min and David each bought two books at the sale.

1. Min's books were priced at $12 and $22. How much did she pay for them?
2. David paid a total of $34.20 for his two books. He paid $5.40 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% $12
Discount	- 10%	- 20%
Sale price	90%	80%	?

(a)
Selling price of the 1st book
= 90% x 22
= ⁹⁰₁₀₀ x 22
= $19.80

Selling price of 2nd book
= 80% x 12
= ⁸⁰₁₀₀ x 12
= $9.60

Total amount that Min paid
= 19.80 + 9.60
= $29.40

	1st book	2nd book	Total amount
Original price	100%	100%
Discount	- 10%	- 20%
Sale price	90%	80%
Compare 1st book and 2nd book	1 u + $5.40	1 u	$34.20

(b)
Sale price of the 1st book = 1 u + 5.40
Sale price of the 2nd book = 1 u

Total amount that David paid
= 1 u + 5.40 + 1 u
= 2 u + 5.40

2 u + 5.40 = 34.20
2 u = 34.20 - 5.40
2 u = 28.80

1 u = 28.80 ÷ 2 = 14.40

Sale price of the 2nd book = $14.40

80% of the price = $14.40
100% of the price = ^14.40₈₀ x 100 = $18

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

Answer(s): (a) $29.40; (b) $18