A can is the shape of a cylinder.
The formula for the volume of a cylinder is Volume = PI x r^2 x h
radius is half the diameter: 5 /2 = 2.5 radius
using 3.14 for PI' we get:
V = 3.14 x 2.5^2 x 6
V = 117.75 cubic inches for the full can
since the can is 75% full multiply the full volume by 0.75
117.75 x 0.75 = 88.3125 cubic inches (round the answer as needed)