PSLE
A stationery kiosk is having a book sale. The 1st book is at 10% 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. Gabby's books were priced at $15 and $23. How much did she pay for them?
2. Howard paid a total of $55.90 for his two books. He paid $12.50 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% $23	100% $15
Discount	- 10%	- 30%
Sale price	90%	70%	?

(a)
Selling price of the 1st book
= 90% x 23
= ⁹⁰₁₀₀ x 23
= $20.70

Selling price of 2nd book
= 70% x 15
= ⁷⁰₁₀₀ x 15
= $10.50

Total amount that Gabby paid
= 20.70 + 10.50
= $31.20

	1st book	2nd book	Total amount
Original price	100%	100%
Discount	- 10%	- 30%
Sale price	90%	70%
Compare 1st book and 2nd book	1 u + $12.50	1 u	$55.90

(b)
Sale price of the 1st book = 1 u + 12.50
Sale price of the 2nd book = 1 u

Total amount that Howard paid
= 1 u + 12.50 + 1 u
= 2 u + 12.50

2 u + 12.50 = 55.90
2 u = 55.90 - 12.50
2 u = 43.40

1 u = 43.40 ÷ 2 = 21.70

Sale price of the 2nd book = $21.70

70% of the price = $21.70
100% of the price = ^21.70₇₀ x 100 = $31

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

Answer(s): (a) $31.20; (b) $31