Let
[tex]x[/tex]
and
[tex]y[/tex]
represent the pairs of whole numbers that have a sum of 40.
This implies that,
[tex]x + y = 40[/tex]
This a single linear equation in two variable. To solve this kind of equation, we make one variable the subject. Say,
[tex]y = 40 - x[/tex]
Since,
[tex]x[/tex]
is a whole number, the domain of the above function is the set of whole numbers.
In order to get a solution, we choose a value for x and then solve for corresponding value of y.
If
[tex]x = - 1[/tex]
[tex]y = 40 - - 1[/tex]
This means,
[tex]y = 40 + 1 = 41[/tex]
Hence,
[tex](-1,41)[/tex]
is one possible solution.
Since the set of whole numbers we can choose for
[tex]x[/tex]
is infinitely many,
[tex]<b>There are infinitely many pairs of whole numbers that can add up to 40</b>[/tex]
