You have:
Cost in dollars --> $2.89
Total ounces --> 4.25
But you want to know the per unit cost for *1* ounce.
You have the right method. You want cost ($) per ounce so put the price over the amount in ounces.
2.89 / 4.25 = x / 1
If you notice, since the denominator is 1, this is simply:
x = 2.89 / 4.25
So the unit cost is just $2.89 divided by the number of ounces (4.25).
Plug that into your calculator and you get:
0.68
That's in dollars. So if you want it in cents, move the decimal point 2 places to the right.
Answer:
$0.68 per ounce
or
68 cents per ounce
