Carl purchased a $242 car stereo at Worst Buy. He paid $28 at the time of purchase and agreed to pay the balance in 12 e...

$$\begin{gathered} The actual price of the car studio = \$242. \\ But since, \$28 has already been paid, the initial value (or the principal amount) will be : \$242 - \$28 = \$214. \\ Also, we are given : \\ Rate \left(r\right) = 14\% \\ Time \left(t\right) = 12 months = 1 year. \end{gathered}$$

$$\begin{gathered} Therefore, the total amount that needs to be paid is given by the formula : \\ A=P(1+rt) \\ A=214(1+(0.14).1) \\ A=214(1+(0.14\left)\right) \\ A=214(1.14) \\ A=243.96 \\ Now we get that the total payable amount, that is the principal amount + all the interest is \$353.8. \\ Now this amount needs to be paid in 12 equal payments. \\ Therefore, the amount that needs to paid in each installment is : \\ \{243.96\}/\left\{12\right\}=20.33 \\ So, each month Carl needs to pay \$20.33 \end{gathered}$$