Answer:
11
Step-by-step explanation:
Whole numbers are all those numbers that are zero or greater then zero, so:
{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, ......}
The list of the pairs is the following:
(0, 10)
(1, 9)
(2, 8)
(3, 7)
(4, 6)
(5, 5)
(6, 4)
(7, 3)
(8, 2)
(9, 1)
(10, 0)
Two pairs with the same numbers, but in different position are not the same thing. They are two different pairs.
For example, (2, 8) and (8, 2) are different. You can imagine them as points on a Cartesian coordinate system to understand why they are different. They are two different points.