Rael and Jenson went to buy projectors at a sale. The usual price of 1 projector was $200 each.

SALE
Buy 1 projector at 15% discount
Buy 2 or more projectors at 20% discount each

1. Rael bought 1 projector. How much did he pay?
2. What is the maximum number of projectors Jenson can buy if he has $4000?

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

100% of 1 projector = 200
1% of 1 projector = 200 ÷ 100 = 2
85% of 1 projector = 85 x 2 = 170 

Amount that Rael paid for 1 projector = $170

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

80% of 1 projector = 80 x 2 = 160

Amount that Jenson paid for 1 projector = $160

Maximum number of projectors that Jenson can buy if he has $4000
= 4000 ÷ 160
= 25 r 0

Answer(s): (a) $170; (b) 25