You add 1 plus another one and you get 2
The sum of 1/2 and 1 1/2 is 2.
the sum of 1 plus 9 is 10 because 1+9
-1
0
The sum of 1 1/3 and 1/3 is 1 2/3
The sum of 1/6 and 1/8 is 7/24
The sum of 1/5 and 1/9 is 14/45
The sum of 1/3 and 1/7 is 10/21
The sum of 1/9 and 1/7 is 16/63
The sum is: 8
(-4) + (5) = 1 [positive one]