Tommy and Ben went to buy hi-fi systems at a sale. The usual price of 1 hi-fi system was $1100 each.

SALE
Buy 1 hi-fi system at 5% discount
Buy 2 or more hi-fi systems at 20% discount each

1. Tommy bought 1 hi-fi system. How much did he pay?
2. What is the maximum number of hi-fi systems Ben can buy if he has $6000?

(a)
Discounted price of 1 hi-fi system in percent if only 1 was bought
= 100% - 5%
= 95%

100% of 1 hi-fi system = 1100
1% of 1 hi-fi system = 1100 ÷ 100 = 11
95% of 1 hi-fi system = 95 x 11 = 1045 

Amount that Tommy paid for 1 hi-fi system = $1045

(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 11 = 880

Amount that Ben paid for 1 hi-fi system = $880

Maximum number of hi-fi systems that Ben can buy if he has $6000
= 6000 ÷ 880
= 6 r 720

Answer(s): (a) $1045; (b) 6