Answer:
Explanation:
$6/(2 DVDs) = $3/DVD, and $8/(4 CDs) = $2/CD
a DVD costs $3
a CD costs $2
Lynn 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)