Shipping box is a cube, with units
Fish food is an unitary cube, that means have x,y,z measures the same
Shipping box is a parallelepip box. Rectangular
Volume of shipping box is found by formula
V = X•Y•Z
X = 3ft, Y=3 3/4 ft, Z=3 1/4 ft
then V = (3•3+ 3•3/4)•(3+1/4) = (11 +1/4)• (3+1/4) = 33 + 11/4 + 3/4 + 1/16
V = 33 + 2 + 3/4+ 3/4 +1/16 = 35 + 25/16 = 34+ 9/16
Now, find volume using packing cubes
How many fish food boxes fit
In X direction it fits 3/(1/4) = 12
In Y direction it fits (3+3/4)/(1/4)= 15
In Z direction it fits (3+1/4)/(1/4) = 10
Now then multiply 12x15x10= 1800 fish boxes fit in larger box