Answer: the cost of each pendant is $2.1
Explanation:
Let x represent the cost of each pendant.
Amy made 3 identical necklaces, each having beads and a pendant. It means that the cost of the pendant used is $3x. The total cost of the beads and pendants for all 3 necklaces was $13.20. If the beads cost a total of $6.90, then the equation would be written as
6.90 + 3x = 13.20
3x = 13.20 - 6.90
3x = 6.3
x = 6.3/3
x = 2.1