This is because for there to be more than 60 dollars left you have to subtract 650 - 60 and it will be 590 left therefore divide it by 23.25 to get 25 and a bunch of unnecessary numbers. I believe a reliable equation would be:
(650 - 60) = 23.25x
590 = 23.25x
x = (Rounded to a whole number) 25
25 is the maximum number of boxes of pens the business assistant can buy
25 boxes because if you divide 590 from 23.25 it equals 25. I got 590 by subtracting 650 and 60 to make sure there is still that remaining 60 in the supply account.
