Bobby and Luke went to buy stereo systems at a sale. The usual price of 1 stereo system was $1900 each.

SALE
Buy 1 stereo system at 5% discount
Buy 2 or more stereo systems at 10% discount each

1. Bobby bought 1 stereo system. How much did he pay?
2. What is the maximum number of stereo systems Luke can buy if he has $7000?

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

100% of 1 stereo system = 1900
1% of 1 stereo system = 1900 ÷ 100 = 19
95% of 1 stereo system = 95 x 19 = 1805 

Amount that Bobby paid for 1 stereo system = $1805

(b)
Discounted price of 1 stereo system in percent if more than 1 was bought
= 100% - 10%
= 90%

90% of 1 stereo system = 90 x 19 = 1710

Amount that Luke paid for 1 stereo system = $1710

Maximum number of stereo systems that Luke can buy if he has $7000
= 7000 ÷ 1710
= 4 r 160

Answer(s): (a) $1805; (b) 4