9514 1404 393
Answer:
 88 ounces
Step-by-step explanation:
Let x represent the number of ounces of the less expensive alloy in the mix. Then the cost of the mix will be ...
 6.75x +10(55) = 8(55+x)
 110 = 1.25x . . . . . . subtract 440+6.75x
 88 = x . . . . . . . . divide by 1.25
88 ounces of $6.75/oz silver must be used.