The total discount in Arlene's purchase was 4.20, this includes the discount applied over both, the case and the charging cord. We already know the original price of the phone case, the discount applied and the value of the discount, use it to find the original price of the chargind cord:
[tex]\begin{gathered} 0.15(18+x)=4.20 \\ 18+x=\frac{4.20}{0.15} \\ 18+x=28 \\ x=28-18 \\ x=10 \end{gathered}[/tex]The original price of the charging cord is $10
