Please help me with this question

$10

Step-by-step explanation:

Assume the price of the phone case is x.

Assume the price of the charging cord is y.

Discounted price for phone case :  15% * x

= 0.15x

Discounted price for charging cord = 0.15y

Expression is therefore:

0.15x + 0.15y = 4.20

0.15 * 18 + 0.15y = 4.20

2.7 + 0.15y = 4.20

0.15y = 4.2 - 2.7

y = 1.5/0.15

y = $10