the sum of all the integers k such that − 26 < k < 24 is
"since k defines a range between − 26 < k < 24 we can set 0 as the reference point for the negative values and positive values . the negative values will range from - 25 to 0 whereas the positive values will range from 0 - 23 . we can conclude that for all but - 25 and - 24 the number pairs will add to 0 . so we have left - 25 - 24 = - 49 . answer d ."
add(add(negate(26), const_1), add(add(negate(26), const_1), const_1))