Question

Neil says his favorite number is 19 units from Sasha's favorite number on the number line. What are the two possibilities for Neil's favorite number?

Answer 1

His favorite number could be either 0 or 38.

Answer 2

Let's make some assumptions:  1) neither favorite number is 0 or less than 0.
2) We need to invent Sasha's favorite number.

If Sasha's favorite number is 20, then 19 less would be 1, and 19 more would be 39.

If Sasha's favorite number were 87, then the two possibilities for Neil's favorite number would be 87-19, or 68,    OR   87+19, or 96.