Unit Price
The store offers a sales pack of 4 necklaces for $48.80. This means each necklace in this pack has a unit price of:
$48.80 / 4 = $12.20
Now we know the unit price of any necklace at Carly's Clothing Store is the same as the unit price at the competing store. This means each necklace at Carly's Clothing Store has a price of $12.20.
If a customer bought 10 of these necklaces, he would have to pay
10 * $12.20 = $122,00
For 10 necklaces at Carly's Clothing Store, a customer would pay $122