#### Answer

a. $C=1500+1.50(n)$ for $0\le n\leq500$
b. 1875 dollars
c. 333 CDs
d. 500 CDs

#### Work Step by Step

a. C=cost, n=# of cds (up to 500)
$C=1500+1.50(n)$ for $0\le n\le 500$
b. $C=1500+1.50(250)$
$C=1500+375$
$C=1875$
c. C=2000
$2000=1500+1.50(n)$
$2000-1500=1.50(n)$
$500=1.50(n)$
$500\div1.50=n$
$n=333$
d. C=3000
$3000=1500+1.50(n)$
$3000-1500=1.50(n)$
$1500=1.50(n)$
$1500\div1.50=n$
$n=1000$ but because the deal is only for up to 500, they can only get 500 CDs.