Valen and Simon went to buy stereo systems at a sale. The usual price of 1 stereo system was $1300 each.

SALE
Buy 1 stereo system at 20% discount
Buy 2 or more stereo systems at 25% discount each

1. Valen bought 1 stereo system. How much did he pay?
2. What is the maximum number of stereo systems Simon can buy if he has $3000?

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

100% of 1 stereo system = 1300
1% of 1 stereo system = 1300 ÷ 100 = 13
80% of 1 stereo system = 80 x 13 = 1040 

Amount that Valen paid for 1 stereo system = $1040

(b)
Discounted price of 1 stereo system in percent if more than 1 was bought
= 100% - 25%
= 75%

75% of 1 stereo system = 75 x 13 = 975

Amount that Simon paid for 1 stereo system = $975

Maximum number of stereo systems that Simon can buy if he has $3000
= 3000 ÷ 975
= 3 r 75

Answer(s): (a) $1040; (b) 3