Harry and Peter went to buy hard drives at a sale. The usual price of 1 hard drive was $200 each.

SALE
Buy 1 hard drive at 20% discount
Buy 2 or more hard drives at 35% discount each

1. Harry bought 1 hard drive. How much did he pay?
2. What is the maximum number of hard drives Peter can buy if he has $4000?

(a)
Discounted price of 1 hard drive in percent if only 1 was bought
= 100% - 20%
= 80%

100% of 1 hard drive = 200
1% of 1 hard drive = 200 ÷ 100 = 2
80% of 1 hard drive = 80 x 2 = 160 

Amount that Harry paid for 1 hard drive = $160

(b)
Discounted price of 1 hard drive in percent if more than 1 was bought
= 100% - 35%
= 65%

65% of 1 hard drive = 65 x 2 = 130

Amount that Peter paid for 1 hard drive = $130

Maximum number of hard drives that Peter can buy if he has $4000
= 4000 ÷ 130
= 30 r 100

Answer(s): (a) $160; (b) 30