Find the exact length of the third side

Ineed to know the answer to this algebra question.

Two numbers have a sum of -19. one number is x. what expression represents the other number?

Identify the function that contains the data in the following table: x     -2         0         2         3         5     f(x)     5         3         1         2         4     possible answers: f(x) = |x| + 1 f(x) = |x - 2| f(x) = |x - 2| - 1 f(x) = |x - 2| + 1