Answer: The box's volume is 9065 in^3 (inches cubed).
Step-by-step explanation: To find the volume of a box (and any regular rectangular prism), you multiply the length, width, and height. In this case, you would do 20 x 18.5 x 24.5, which would give you the answer of 9065 in^3.
*Notes: I wrote the 1/2 as a decimal, tagging the .5 on at the end of the number, instead of as a fraction.
The unit at the end of the calculation is inches cubed (to the exponent 3) because the box occupies a three-dimensional space.