For a problem like this, you'll want to break it down ...
Total cost = $19.60.
Cost of beads = $12.80.
Cost of pendant = ?
We know that there are 4 necklaces. Each necklace has one pendant, so we have 5 pendants total. Therefore, your solution should look something like this ...
Total cost = Cost of beads - cost of pendant
$19.60 = 12.80 - 4x <- x is the variable representing the price for a single pendant.
6.80 = 4x <- Subtract 12.80 from both sides.
x = 1.70 <- Divide both sides by 4, and find your final answer.
x = 1.70; therfore, each pendant costs $1.70.
