How many pairs of whole numbers have sum of 110

Because the number is even, then the number of possible combinations will be: 110/2 = 55 let's consider a simpler example, the number: 10, then we have: 10+0, 9+1, 8+2, 7+3, 6+4, which is equal to 10/2 = 5 combinations. Note: We are not considering permutations between the elements of the sum therefore 10+0, 0+10 counts as one combination.