Simon fills a container with 38 1−in. cubes. A prism with a length of 4 inches, height of 4 inches, and width of 3 inches. How many more

If the prism (the box) has dimension 4" x 4" x 3", its volume is 48 cu. in.

If you place 38 1" cubes into this box, there is still room for 48 - 38  =  10 more 1" cubes.