Since you haven't provided the radius, I'll just use the symbol 'r' to refer to radius. You can substitute with the given radius in the equation.
Now, circumference of the circle is calculated using the following rule: curcimference of circle = 2*pi*r where: r is the radius pi is given as 3.14 Therefore: circumference of circle = 2*3.14*r = 6.28 r units
Unit rate is (cost) per 1 unit the unit is fluid oz 'per' is fraction cost/1unit so we do 2.56/32 divide completely 2.56/32=0.08/1 the unit rate is $0.08 per oz