Answer
$3.5x+2.5y=121$
$9x+7.5y=324$
Work Step by Step
Let's x = the number of necklaces
y = the number of bracelets
The total cost of material to make necklaces and bracelets:
$3.5x+2.5y=121$
The total income:
$9x+7.5y=324$
Hence the system of equations is:
$3.5x+2.5y=121$
$9x+7.5y=324$