Answer
$7
Explaination :
3 bracelet - $5( for 1)
3 necklace - (unknown)
Total amount paid - $40
change - $4
Calculation for all 3 bracelet
$5×3=$15
Calculation for the real amount
$40-$4=$36
Calculation for 3 necklace
$36-$15=$21
Calculation for 1 necklace
$21÷3=$7
There reason I divide it with 3 was because I got the total amount for 3necklace now I only want 1..
Final answer - $7#
Hope this helped :)