Ken and Riordan went to buy hi-fi systems at a sale. The usual price of 1 hi-fi system was $1800 each.

SALE
Buy 1 hi-fi system at 15% discount
Buy 2 or more hi-fi systems at 25% discount each

1. Ken bought 1 hi-fi system. How much did he pay?
2. What is the maximum number of hi-fi systems Riordan can buy if he has $2000?

(a)
Discounted price of 1 hi-fi system in percent if only 1 was bought
= 100% - 15%
= 85%

100% of 1 hi-fi system = 1800
1% of 1 hi-fi system = 1800 ÷ 100 = 18
85% of 1 hi-fi system = 85 x 18 = 1530 

Amount that Ken paid for 1 hi-fi system = $1530

(b)
Discounted price of 1 hi-fi system in percent if more than 1 was bought
= 100% - 25%
= 75%

75% of 1 hi-fi system = 75 x 18 = 1350

Amount that Riordan paid for 1 hi-fi system = $1350

Maximum number of hi-fi systems that Riordan can buy if he has $2000
= 2000 ÷ 1350
= 1 r 650

Answer(s): (a) $1530; (b) 1