Perry and Dylan went to buy hi-fi systems at a sale. The usual price of 1 hi-fi system was $400 each.

SALE
Buy 1 hi-fi system at 10% discount
Buy 2 or more hi-fi systems at 20% discount each

1. Perry bought 1 hi-fi system. How much did he pay?
2. What is the maximum number of hi-fi systems Dylan can buy if he has $3000?

(a)
Discounted price of 1 hi-fi system in percent if only 1 was bought
= 100% - 10%
= 90%

100% of 1 hi-fi system = 400
1% of 1 hi-fi system = 400 ÷ 100 = 4
90% of 1 hi-fi system = 90 x 4 = 360 

Amount that Perry paid for 1 hi-fi system = $360

(b)
Discounted price of 1 hi-fi system in percent if more than 1 was bought
= 100% - 20%
= 80%

80% of 1 hi-fi system = 80 x 4 = 320

Amount that Dylan paid for 1 hi-fi system = $320

Maximum number of hi-fi systems that Dylan can buy if he has $3000
= 3000 ÷ 320
= 9 r 120

Answer(s): (a) $360; (b) 9