Heckin?
The price per ounce is the price divided by the number of ounces. We have to divide the cost by the amount to get this for each brand.
We don't really. We can see both X=9.75/8.5 and Z=19.48/13.5 are bigger than a dollar per ounce, so bigger than W=8.75/10=0.875 dollars per ounce and Y=18.25/25.
So the only question is if Y<W?
We divide by 25 by multiplying by four then dividing by 100,
Y = 0.73 dollars per ounce
Answer: Y has the lowest unit cost