Answer
a. $ \$7.6$
b. No, you cannot buy 3 more CD's. You could still buy 2. You would need an extra $\$3.50$ to buy 3 CDs ....But who still buys CD's, anyway?!
Work Step by Step
a. $\$30.40 = 4 \cdot x$
$x = \$7.60$
Each CD costs $\$7.60.$ (Note: This assumes there is no sales tax, shipping, or other fee)
b. You have $\$25$.
The regular price of the CDs is $\frac{7.6}{x}* \frac{80}{100}$ or $\$9.5$ (Cross multiply & divide the proportion to solve)
$\$9.5\times3 =\$28.5$
$\$28.5>\$25$
