First we have to subtract the computer length from the table length to find how much room there will be left on the table 28 3/4-24 2/4=4 1/4 and now since he wants it in the center we will divide that number by 2 because there will be some room on either side of the computer 4 1/4 divided by 2 is 2 1/8
I hope this helps and please don't hesitate to ask if there is anything still unclear!
