Question

At a garage sale, a large bin full of DVDs and CDs are being sold. All the DVDs are the same price, and all the CDs are the same price.

Aleah buys 2 DVDs for $6 and 4 CDs for $8. Her friend, Ling, wants to buy 4 DVDs and 2 CDs. How much will Ling have to pay?

Aleah's brother, Pierre, wants to spend $20 on DVDs and CDs. What combination of DVDs and CDs could he buy?

Answer 1

Explanation:

$6/(2 DVDs) = $3/DVD, and $8/(4 CDs) = $2/CD

a DVD costs $3

a CD costs $2

Ling bought 4 DVDs and 2 CDs for 4×$3 + 2×$2 = $16.

Pierre bought d DVDs and c CDs for $20.

d is 0, 2, 4, or 6

c = (20-3d)/2

(d,c) = (0,10), (2,7), (4,4), or (6,1)