Nick and Justin went to buy projectors at a sale. The usual price of 1 projector was $1000 each.

SALE
Buy 1 projector at 10% discount
Buy 2 or more projectors at 15% discount each

1. Nick bought 1 projector. How much did he pay?
2. What is the maximum number of projectors Justin can buy if he has $5000?

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

100% of 1 projector = 1000
1% of 1 projector = 1000 ÷ 100 = 10
90% of 1 projector = 90 x 10 = 900 

Amount that Nick paid for 1 projector = $900

(b)
Discounted price of 1 projector in percent if more than 1 was bought
= 100% - 15%
= 85%

85% of 1 projector = 85 x 10 = 850

Amount that Justin paid for 1 projector = $850

Maximum number of projectors that Justin can buy if he has $5000
= 5000 ÷ 850
= 5 r 750

Answer(s): (a) $900; (b) 5