The volume of a cube is then (6.75cm)^3. Here the units are cubic centimeters or cm^3. Since there are 2.54 cm in 1 inch [exact] and 12 inches in 1 foot, the volume of the cube is (6.75 cm)^3 * (1 inch/2.54cm)^3 * (1 ft/12 inch)^3. 0.01086 ft^3 is your answer
I think that 5/3 is not equivalent to this numbers because 2/3 cannot be written in another as 5/3. It can only be written as 6/9 or 4/6. Im not entirely sure but i hope this helped.